How to troubleshoot intermittent WAN connection drops?

jholmes07

Occasional Visitor
Every 4/5 days, my internet connection drops and I have to reboot the modem for it to start working again. LAN and local network works perfectly fine but cant access google or anything on any of my devices.

I have been trying to get to the bottom of my internet interruptions for the better part of 3 years and i still dont cant figure out what the problem is. ISP is no help. They just blame the modem which I own. Modem manufacturer is no help. They just blame the ISP.

Things I’ve tried:

1. Swapped router 3x times. Same model but exchanged through warranty. Assumed it was the router initially.
2. Had ISP come check COAX cables.
3. I moved! A whole address and problems persisted
4. Had ISP install splitter of some kind between modem and COAX cable to increase upstream/downstream power levels at the insistence of modem manufacturer.
5. New modem through warranty.
6. Ensure upstream/downstream power levels and other settings in modem is correct and at proper levels with the assistance of modem manufacturer.

Only thing that worked was giving in to renting the ISP modem but i refuse to believe that is the only reason. This also leads me to believe the ISP is intentionally sabotaging my connection because I refuse to rent their modem.

My question is how do I troubleshoot to get to the bottom of why this is happening? Is there any logs i can check? What do i look for?

My equipment:
Arris SB8200 Cable Modem
Asus RT-AC86U with latest Merlin firmware
Various networking equipment including echos, two laptops, NAS with docker software for torrenting and VPN, phones, tablets, Shield TV, Apple TV etc.


ISP is Optimum/Altice
 

degrub

Very Senior Member
A few ideas -

Are you sure the issue is with the modem or the router ?
What do the system logs on the modem and router show when the drop occurs ?

What type of connection protocol is being used ?
Is this possibly a connection lease time out ?

Do they provide a list of compatible modem model numbers ?
If so, and you have one, escalate up tech support until you get someone who can figure it out. File a complaint with the FCC and others.
If the modem you have is not on their supported list, then get one that is.

What was the ISP modem manufacturer and model number ?

Does the issue happen at a specific time of day ?
Is your modem and router on a UPS battery backup ?
 

Tech Junky

Very Senior Member
@degrub

I suppose you have a point there. If I had to swap the CM / Router 3X though I would be looking at new options.

For the CM I would swap to a MB8600 or if you want higher bandwidth options there's a newer version with a 2.5GE port on it.MB8611

Router is probably not the issue but, if it is then maybe switch to an EERO Pro 6E - Single pack release 5/4 @ $299 / dual pack $499
 

degrub

Very Senior Member
another long shot suggestion- swap out the ethernet cable between the router wan port and the modem lan port with a new CAT5E cable.
 

jholmes07

Occasional Visitor
A few ideas -

Are you sure the issue is with the modem or the router ? I'm 95% sure its not the router. As mentioned rebooting the modem fixes it. This suggest to me the issue is happening in the modem either due to the isp signal or some configuration on the modem
What do the system logs on the modem and router show when the drop occurs ? idk how to access the log on the modem. and i dont understand the routers logs. This is main purpose of this post. to see if anyone can direct me to somewhere i can learn how to investigate this further

What type of connection protocol is being used ? ??...uhh cable?
Is this possibly a connection lease time out ? How would I find out?

Do they provide a list of compatible modem model numbers ? not that i could find but Arris website says this is compatible with most cable internet provider. The technicians that installed my service never complained about it. My previous model was similar and was in service for half a decade with no issues.
If so, and you have one, escalate up tech support until you get someone who can figure it out. File a complaint with the FCC and others.
If the modem you have is not on their supported list, then get one that is. Might end up going this route. thanks.

What was the ISP modem manufacturer and model number ? This ISP typical uses ARRIS modems as well but usually the TM822, TM804 or the TM1602 models.

Does the issue happen at a specific time of day ? no. random times but usually after 4/5 of use.
Is your modem and router on a UPS battery backup ? no

Thanks for all the feedback.
 

jholmes07

Occasional Visitor

Puma presents its own issues with the CM.

I use a MB8600 and it's been flawless for several years.

Quote from a review in 2017:

Hardware
Inside the case, Arris has equipped the SB8200 with a Broadcom BCM3390 chipset (a much needed change from the SB6190’s Intel Puma 6 chipset), 3 GB of RAM, 128MiB S34ML01G200TFV00 Spansion flash memory NAND and 16 MiB Macronix MX25L12805D SPI NAND flash memory. The SB8200 should be able to handle downstream bonded channels up to 32 SCQAM or 2 OFDM and upstream bonded channels up to 8 SCQAM or 2 OFDMA.
 

degrub

Very Senior Member
Thanks for all the feedback.
you should have username/password access to the modem - same as you used for the setup, probably on the lan port.. i don't know all the pages, but there will be something for system logs, communication log, etc. Snip copies from the time just before and through the re-boot from both the modem and the router, please. Post the snip file in this thread. Others with more familiarity than myself should be able to interpret or at least get you going in the right direction.
 

Tech9

Part of the Furniture
1. Swapped router 3x times. Same model but exchanged through warranty. Assumed it was the router initially.

Have you tried with a different non-Asus router? There are multiple threads here on SNB about Asus routers having issues with different modems. All your experiments are with the same Arris modem and the same Asus router. They may not want to work well together.
 

jholmes07

Occasional Visitor
you should have username/password access to the modem - same as you used for the setup, probably on the lan port.. i don't know all the pages, but there will be something for system logs, communication log, etc. Snip copies from the time just before and through the re-boot from both the modem and the router, please. Post the snip file in this thread. Others with more familiarity than myself should be able to interpret or at least get you going in the right direction.

These are the logs from my modem. Thanks!

Date Time Event ID Event Level Description
04/18/2022 05:02 67050300 5 "DBC-REQ Mismatch Between Calculated Value for P1.6hi Compared to CCAP Provided Value;CM-MAC=xx:xx:xx:xx:xx:xx;CMTS-MAC=xx:xx:xx:xx:xx:xx;CM-QOS=1.1;CM-VER=3.1;"
04/18/2022 05:02 84000500 3 "SYNC Timing Synchronization failure - Loss of Sync;CM-MAC=xx:xx:xx:xx:xx:xx;CMTS-MAC=xx:xx:xx:xx:xx:xx;CM-QOS=1.1;CM-VER=3.1;"
04/18/2022 04:50 69010600 4 "SW upgrade Failed before download - TFTP Max Retry Exceeded"
04/18/2022 04:50 69010200 6 "SW Download INIT - Via Config file ^1/xxxxxxxx/xxxxxxxxxx/VER=D31"
04/18/2022 04:50 2436694061 5 "Dynamic Range Window violation"
04/18/2022 04:50 82001200 5 "RNG-RSP CCAP Commanded Power in Excess of 6 dB Below the Value Corresponding to the Top of the DRW;CM-MAC=xx:xx:xx:xx:xx:xx;CMTS-MAC=xx:xx:xx:xx:xx:xx;CM-QOS=1.1;CM-VER=3.1;"
04/18/2022 04:50 2436694061 5 "Dynamic Range Window violation"
04/18/2022 04:50 82001200 5 "RNG-RSP CCAP Commanded Power in Excess of 6 dB Below the Value Corresponding to the Top of the DRW;CM-MAC=xx:xx:xx:xx:xx:xx;CMTS-MAC=xx:xx:xx:xx:xx:xx;CM-QOS=1.1;CM-VER=3.1;"
04/18/2022 04:50 2436694061 5 "Dynamic Range Window violation"
04/18/2022 04:50 82001200 5 "RNG-RSP CCAP Commanded Power in Excess of 6 dB Below the Value Corresponding to the Top of the DRW;CM-MAC=xx:xx:xx:xx:xx:xx;CMTS-MAC=xx:xx:xx:xx:xx:xx;CM-QOS=1.1;CM-VER=3.1;"
04/18/2022 04:50 73050400 5 "REG-RSP-MP Mismatch Between Calculated Value for P1.6hi Compared to CCAP Provided Value;CM-MAC=xx:xx:xx:xx:xx:xx;CMTS-MAC=xx:xx:xx:xx:xx:xx;CM-QOS=1.1;CM-VER=3.1;"
04/18/2022 04:50 67061600 6 "DS profile assignment change. DS Chan ID: 32; Previous Profile: ; New Profile: 1 2 3.;CM-MAC=xx:xx:xx:xx:xx:xx;CMTS-MAC=xx:xx:xx:xx:xx:xx;CM-QOS=1.1;CM-VER=3.1;"
04/18/2022 04:50 73040100 6 "TLV-11 - unrecognized OID;CM-MAC=xx:xx:xx:xx:xx:xx;CMTS-MAC=xx:xx:xx:xx:xx:xx;CM-QOS=1.1;CM-VER=3.1;"
04/18/2022 04:50 68000300 5 "DHCP WARNING - Non-critical field invalid in response ;CM-MAC=xx:xx:xx:xx:xx:xx;CMTS-MAC=xx:xx:xx:xx:xx:xx;CM-QOS=1.1;CM-VER=3.1;"
01/01/1970 00:00 2436694066 6 "Honoring MDD; IP provisioning mode = IPv4"
01/01/1970 00:00 84000100 3 "SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=xx:xx:xx:xx:xx:xx;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.1;CM-VER=3.1;"
04/15/2022 09:44 84000500 3 "SYNC Timing Synchronization failure - Loss of Sync;CM-MAC=xx:xx:xx:xx:xx:xx;CMTS-MAC=xx:xx:xx:xx:xx:xx;CM-QOS=1.1;CM-VER=3.1;"
01/01/1970 00:02 82000200 3 "No Ranging Response received - T3 time-out;CM-MAC=xx:xx:xx:xx:xx:xx;CMTS-MAC=xx:xx:xx:xx:xx:xx;CM-QOS=1.1;CM-VER=3.1;"
01/01/1970 00:02 84000100 3 "SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=xx:xx:xx:xx:xx:xx;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.1;CM-VER=3.1;"
01/01/1970 00:00 84000100 3 "SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=xx:xx:xx:xx:xx:xx;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.1;CM-VER=3.1;"
 

Tech Junky

Very Senior Member
Only thing that worked was giving in to renting the ISP modem but i refuse to believe that is the only reason. This also leads me to believe the ISP is intentionally sabotaging my connection because I refuse to rent their modem.
This seems funny in that BYOCM has been a thing for a couple of decades and as long as the MAC is tied to your account it should be provisioned and work just fine. Now, you've swapped the CM and MOVED so, theoretically you should be on a totally different node going back to the CMTS.

Personally I would escalate the issue to a Tier 3 level and get them to send actual engineers out to look at why this is happening or switch to a FWA option and ditch them completely.

Based on these I would say there's a provider issue or a splitter that's going bad anywhere from the DMARC to your CM.
----------------------------------------------------------------------------------------------------------------------------------------------------------
"Dynamic range window violations occur when there's more than a certain variation in the power levels. Hard part is that when you pull the connections page is that it takes the snapshot at the time you access it. If the error is brief, you'll miss the variation when you pull up the page. If both you and your neighbor are getting these errors, I'd have your isp inspect your neighbor hood box/lines. If its a single user it tends to be from the box to the users house but if multiples are getting it, something else is causing the problems.

Could also be, the upstream transmitters are outside of the maximum range differences (12db) - this potentially can be caused by noise on a specific upstream frequency."

RNG-RSP CCAP Commanded Power in Excess of 6 dB Below the Value Corresponding to the Top of the DRW:

"When the upstream power is too high / out of spec, this can cause random drops and spontaneous rebooting of the modem, speed, packet loss, latency problems, unbonding of channels.

Troubleshooting: check for unneeded splitters that can be eliminated. Try cleaning / tightening connections. Clean off any oxidation from center wire."

DHCP RENEW WARNING - Field invalid in response v4 option;CM-MAC= ;CMTS-MAC= ;CM-QOS=1.1;CM-VER=3.1;

"The modem has an internal IP address on Cable network. About half way through the lease period, the modem will automatically attempt to renew that lease. There were extensions added to the DHCP protocol in preparation for DHCPv4 / DHCPv6 interoperability. This means that there are a number of options transmitted with the DHCP responses that are not recognized by standard DHCP clients but generally inconsequential particularly in a IPV4 network. The modem’s DHCP client is a basic client so it can’t process the DHCP extensions so it throws the invalid field warning but completes the DHCP operation with the non-extended fields without issue. The frequency / occurrence of this message is dependent on the modem model, firmware, and CMTS / Modem configuration. This message can safely be ignored."

Started Unicast Maintenance Ranging - No Response received - T3 time-out.

"T3 time out - The cable modem has sent 16 Ranging Request (RNG-REQ) messages without receiving a Ranging Response (RNG-RSP) message in reply from the CMTS. The cable modem is therefore resetting its cable interface and restarting the registration process. This typically is caused by noise on the upstream that causes the loss of MAC-layer messages. Noise could also raise the signal-to-noise ratio (SNR) on the upstream to a point where the cable modem’s power level is insufficient to transmit any messages. If the cable modem cannot raise its upstream transmit power level to a level that allows successful communication within the maximum timeout period, it resets its cable interface and restarts the registration process. This error message is DOCSIS event message is R03.0, Ranging Request."

I also got these two codes - the first I think is just a downstream channel change, but not sure what the second is for:

DS profile assignment change. DS Chan ID: 32; Previous Profile: ; New Profile: 1 2 3.;CM-MAC= ;CMTS-MAC= ;CM-QOS=1.1;CM-VER=3.1;

REG-RSP-MP Mismatch Between Calculated Value for P1.6hi Compared to CCAP Provided Value;CM-MAC= ;CMTS-MAC=
;CM-QOS=1.1;CM-VER=3.1;
 

jholmes07

Occasional Visitor
This seems funny in that BYOCM has been a thing for a couple of decades and as long as the MAC is tied to your account it should be provisioned and work just fine. Now, you've swapped the CM and MOVED so, theoretically you should be on a totally different node going back to the CMTS.

Personally I would escalate the issue to a Tier 3 level and get them to send actual engineers out to look at why this is happening or switch to a FWA option and ditch them completely.

Based on these I would say there's a provider issue or a splitter that's going bad anywhere from the DMARC to your CM.
----------------------------------------------------------------------------------------------------------------------------------------------------------
"Dynamic range window violations occur when there's more than a certain variation in the power levels. Hard part is that when you pull the connections page is that it takes the snapshot at the time you access it. If the error is brief, you'll miss the variation when you pull up the page. If both you and your neighbor are getting these errors, I'd have your isp inspect your neighbor hood box/lines. If its a single user it tends to be from the box to the users house but if multiples are getting it, something else is causing the problems.

Could also be, the upstream transmitters are outside of the maximum range differences (12db) - this potentially can be caused by noise on a specific upstream frequency."

RNG-RSP CCAP Commanded Power in Excess of 6 dB Below the Value Corresponding to the Top of the DRW:

"When the upstream power is too high / out of spec, this can cause random drops and spontaneous rebooting of the modem, speed, packet loss, latency problems, unbonding of channels.

Troubleshooting: check for unneeded splitters that can be eliminated. Try cleaning / tightening connections. Clean off any oxidation from center wire."

DHCP RENEW WARNING - Field invalid in response v4 option;CM-MAC= ;CMTS-MAC= ;CM-QOS=1.1;CM-VER=3.1;

"The modem has an internal IP address on Cable network. About half way through the lease period, the modem will automatically attempt to renew that lease. There were extensions added to the DHCP protocol in preparation for DHCPv4 / DHCPv6 interoperability. This means that there are a number of options transmitted with the DHCP responses that are not recognized by standard DHCP clients but generally inconsequential particularly in a IPV4 network. The modem’s DHCP client is a basic client so it can’t process the DHCP extensions so it throws the invalid field warning but completes the DHCP operation with the non-extended fields without issue. The frequency / occurrence of this message is dependent on the modem model, firmware, and CMTS / Modem configuration. This message can safely be ignored."

Started Unicast Maintenance Ranging - No Response received - T3 time-out.

"T3 time out - The cable modem has sent 16 Ranging Request (RNG-REQ) messages without receiving a Ranging Response (RNG-RSP) message in reply from the CMTS. The cable modem is therefore resetting its cable interface and restarting the registration process. This typically is caused by noise on the upstream that causes the loss of MAC-layer messages. Noise could also raise the signal-to-noise ratio (SNR) on the upstream to a point where the cable modem’s power level is insufficient to transmit any messages. If the cable modem cannot raise its upstream transmit power level to a level that allows successful communication within the maximum timeout period, it resets its cable interface and restarts the registration process. This error message is DOCSIS event message is R03.0, Ranging Request."

I also got these two codes - the first I think is just a downstream channel change, but not sure what the second is for:

DS profile assignment change. DS Chan ID: 32; Previous Profile: ; New Profile: 1 2 3.;CM-MAC= ;CMTS-MAC= ;CM-QOS=1.1;CM-VER=3.1;

REG-RSP-MP Mismatch Between Calculated Value for P1.6hi Compared to CCAP Provided Value;CM-MAC= ;CMTS-MAC=
;CM-QOS=1.1;CM-VER=3.1;
Thank you very much for the detailed response.

I stopped trying to call the ISP because as soon as you mention you have your own modem they blame it on that and refuse to troubleshoot further. I will give it another shot.

At the insistence of the modem manufacturer I had the ISP increase power levels. ISP accomplished this by installing a splitter between the modem and coax. I will try removing this and see what happens.

I also have the snapshot of the status page. I forgot to add. The power levels are always at the recommended levels whether the system is working or not.

Thanks again.
 

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Tech Junky

Very Senior Member
For me removing all splitters worked better than trying to squeeze the RF signal into the spec range for optimal stability. I have better speeds and stability hasn't been an issue. Then again the only thing on the coax is the modem so there's no need to split to TV/STB's for video. If there was a need I would do a single 2-way splitter 1 direct to the CM and the other to everything else.

Basically here's what the lines coming into the BLDG look like.

Hardline external <> 8-port tap <> my unit <> CM

The closet has a pre-wired 12 port "hub" that goes to every wall w/ an outlet. The DB loss through that thing though is too much for a good signal. Bypassing it boosted the signal / speed / stability. Using a good splitter though makes all the difference compared to the junk that gets installed sometimes. I just spliced together the run coming from the TAP to the CM using the outlet connecter from a wall plate to splice together the 2 lines.
 

jholmes07

Occasional Visitor
This seems funny in that BYOCM has been a thing for a couple of decades and as long as the MAC is tied to your account it should be provisioned and work just fine. Now, you've swapped the CM and MOVED so, theoretically you should be on a totally different node going back to the CMTS.

Personally I would escalate the issue to a Tier 3 level and get them to send actual engineers out to look at why this is happening or switch to a FWA option and ditch them completely.

Based on these I would say there's a provider issue or a splitter that's going bad anywhere from the DMARC to your CM.
----------------------------------------------------------------------------------------------------------------------------------------------------------
"Dynamic range window violations occur when there's more than a certain variation in the power levels. Hard part is that when you pull the connections page is that it takes the snapshot at the time you access it. If the error is brief, you'll miss the variation when you pull up the page. If both you and your neighbor are getting these errors, I'd have your isp inspect your neighbor hood box/lines. If its a single user it tends to be from the box to the users house but if multiples are getting it, something else is causing the problems.

Could also be, the upstream transmitters are outside of the maximum range differences (12db) - this potentially can be caused by noise on a specific upstream frequency."

RNG-RSP CCAP Commanded Power in Excess of 6 dB Below the Value Corresponding to the Top of the DRW:

"When the upstream power is too high / out of spec, this can cause random drops and spontaneous rebooting of the modem, speed, packet loss, latency problems, unbonding of channels.

Troubleshooting: check for unneeded splitters that can be eliminated. Try cleaning / tightening connections. Clean off any oxidation from center wire."

DHCP RENEW WARNING - Field invalid in response v4 option;CM-MAC= ;CMTS-MAC= ;CM-QOS=1.1;CM-VER=3.1;

"The modem has an internal IP address on Cable network. About half way through the lease period, the modem will automatically attempt to renew that lease. There were extensions added to the DHCP protocol in preparation for DHCPv4 / DHCPv6 interoperability. This means that there are a number of options transmitted with the DHCP responses that are not recognized by standard DHCP clients but generally inconsequential particularly in a IPV4 network. The modem’s DHCP client is a basic client so it can’t process the DHCP extensions so it throws the invalid field warning but completes the DHCP operation with the non-extended fields without issue. The frequency / occurrence of this message is dependent on the modem model, firmware, and CMTS / Modem configuration. This message can safely be ignored."

Started Unicast Maintenance Ranging - No Response received - T3 time-out.

"T3 time out - The cable modem has sent 16 Ranging Request (RNG-REQ) messages without receiving a Ranging Response (RNG-RSP) message in reply from the CMTS. The cable modem is therefore resetting its cable interface and restarting the registration process. This typically is caused by noise on the upstream that causes the loss of MAC-layer messages. Noise could also raise the signal-to-noise ratio (SNR) on the upstream to a point where the cable modem’s power level is insufficient to transmit any messages. If the cable modem cannot raise its upstream transmit power level to a level that allows successful communication within the maximum timeout period, it resets its cable interface and restarts the registration process. This error message is DOCSIS event message is R03.0, Ranging Request."

I also got these two codes - the first I think is just a downstream channel change, but not sure what the second is for:

DS profile assignment change. DS Chan ID: 32; Previous Profile: ; New Profile: 1 2 3.;CM-MAC= ;CMTS-MAC= ;CM-QOS=1.1;CM-VER=3.1;

REG-RSP-MP Mismatch Between Calculated Value for P1.6hi Compared to CCAP Provided Value;CM-MAC= ;CMTS-MAC=
;CM-QOS=1.1;CM-VER=3.1;
Thanks man for recommending me to have them come out. I did just that and they were able to identify the cable coming into my house was badly damaged/cut (probably from a window replacement the month prior, the line comes in near the base of the window). It’s been over 1 week of solid up time with no drops. I think my issues are finally solved. Thanks a lot. You saved my life haha.

Now if i can just figure out why my Remote Desktop connection to my office intermittently drops every few seconds, my life would be golden. But I think this problem is unrelated so I will try to figure it out. Thanks again.
 

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