MoCA Losing some Upstream Channels when adding splitter

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Mark070

Regular Contributor
Hey Guys,

I have been running a MoCA network for awhile now. Recently I swapped out two of my adapters for two of the goCoax 2.5 adapters. I have a 200/10 internet plan.
Right now, I have the coax going into one of the goCoax adapters, and a line coming out of the TV port into the cable modem. I have a picture (attached) showing what the cable modem looks like when using this setup.
If I change the setup to add a moca compatible 2-way splitter (I have tried multiple different types and even a POE filter in front of the cable modem), I instantly lose two of the Upstream bonded channels. Eventually, I lose three of the upstream channels and the modem will reset and cause the router to also reboot.

If I leave my current configuration is as, I dont have any issues - but, once in awhile, the adapter has an issue and instantly caps my network speed to 40 down. If I unplug and plug it back in, the adapter resets and voila, back to normal.

Does anyone have a guess as to why I lose my upstream channels the moment I add a splitter? the numbers look ok. My cable Modem is a Netgear CM600. If I recall, I lose the higher frequency upstream channels.
 

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degrub

Very Senior Member
too much signal loss between the modem and the ISP.
The splitter adds about 3.5dB loss to the line.
You may have to use an amplified splitter - a 0 gain MOCA powered splitter should work if your current setup doesn't have issues. If it does, you likely need additional amplification in the signal path.

A full map of your coax would be helpful to identify the best location for an amp. It may be that you can amplify at the first entry to your house.
Have you talked with the ISP about increasing the power from their end ? Particularly if you are intermittently loosing bandwidth as is.
 

krkaufman

Senior Member
too much signal loss between the modem and the ISP.
The splitter adds about 3.5dB loss to the line.
You may have to use an amplified splitter ...

A full map of your coax would be helpful to identify the best location for an amp.
This. And a detailed description or diagram (however rough) of your coax plant might highlight an alternative to a powered amp, depending on how the coax run to the modem location is currently split off the coax plant. The preferred approach is using a 2-way splitter as the top-level splitter, to get the maximum signal strength (passively) possible to the modem.

e.g.
PoE and protective MoCA filters.png
 

krkaufman

Senior Member
If I leave my current configuration is as, I dont have any issues - but, once in awhile, the adapter has an issue and instantly caps my network speed to 40 down. If I unplug and plug it back in, the adapter resets and voila, back to normal.
Does this occur even if the modem (CM600) is protected by a separate MoCA filter?
 

Mark070

Regular Contributor
Ok, sorry for the delay. I think I understand what you guys are saying. I had a hunch, and I think you guys are right. I have attach a very crude diagram of my MoCA network, its a very simple network. The picture is the way I want it to be (using a 2 way splitter near the cable modem). This way also is only getting me a max of two upstream channels. If I have the coax go into the MoCA adapter, and then into my Cable Modem, I get all four channels.

If you are suggesting a signal boost, could you link me one that would work? I assume you would want one at the entry point, ideally with a built in POE Filter

I have a video of my network (its about a year old, and the MoCA adapters are not goCoax, but the layout is the same and its want I want (using a splitter) - you only really need the first 40 seconds.
 

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degrub

Very Senior Member
If your modem is in a different room from the entry 4 way splitter, try placing the two way splitter just behind the POE filter as shown connecting one leg to the 4 way and the other leg directly to the cable going to the room with the modem. You should get only 3.5 dB loss instead of 7.5 dB which may be enough to make a difference. Can you use the TV band pass through on the moca modem to pass the signal to your ISP modem ?

Otherwise, the 4 way likely needs to be powered as described earlier. 0 dB gain is likely good enough based on what you described and if using the two leg splitter at the entry end works for the ISP modem.
 

Mark070

Regular Contributor
I will have to wait to find time, I dont have a line tester to determine which line goes directly to cable modem, will have to be trial and error.

regarding a powered solution, do you have a link on something I would need to purchase if the above solution does not work?
 

degrub

Very Senior Member
I believe that was one of the amps mentioned in other threads with positive results. You should not need to use your poe filter on the input coax.
 

krkaufman

Senior Member
This. And a detailed description or diagram (however rough) of your coax plant might highlight an alternative to a powered amp, depending on how the coax run to the modem location is currently split off the coax plant. The preferred approach is using a 2-way splitter as the top-level splitter, to get the maximum signal strength (passively) possible to the modem.

e.g.
Seeing your diagram, that you're using a 4-way passive distribution splitter, it would seem that inserting a 2-way splitter as your top-level splitter would provide you with a slight overall signal improvement from your pass-through approach... -7 dB total (2x 3.5 dB) vs approximately -8 dB (4-way + loss through MoCA adapter). A powered amplifier shouldn't be necessary.

Same as in my earlier diagram, but using your graphics approach...

MoCA Layout. alt.jpg
 

krkaufman

Senior Member
p.s. The (DOCSIS passive) Amphenol hybrid splitter might also be worth trying, as an alternative to the top-level 2-way splitter approach ... replacing the function of the "PoE" MoCA filter, 2-way and 4-way in the above diagram with a single component (though you'd want to grab some 75-ohm terminators to cap unused ports).

See: https://www.amphenolbroadband.com/docsis-passive/

Buy: https://www.amazon.com/dp/B07CQTHL33/?tag=snbforums-20


MoCA Layout hybrid.jpg


edit: * ... plus add'l loss of the coax jumper & connections between the "PoE" MoCA filter and top-level 2-way splitter.
 
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krkaufman

Senior Member
I will have to wait to find time, I dont have a line tester to determine which line goes directly to cable modem, will have to be trial and error.
A coax tester (e.g.) can be helpful to streamline the line identification process. Otherwise, yeah, it's just a matter of disconnecting lines until the modem sync is lost.
 

Mark070

Regular Contributor
p.s. The (DOCSIS passive) Amphenol hybrid splitter might also be worth trying, as an alternative to the top-level 2-way splitter approach ... replacing the function of the "PoE" MoCA filter, 2-way and 4-way in the above diagram with a single component (though you'd want to grab some 75-ohm terminators to cap unused ports).

See: https://www.amphenolbroadband.com/docsis-passive/

Buy: https://www.amazon.com/dp/B07CQTHL33/?tag=snbforums-20


View attachment 27955

edit: * ... plus add'l loss of the coax jumper & connections between the "PoE" MoCA filter and top-level 2-way splitter.
I like this splitter you linked. For the MoCA Adapters (the top 3), wouldn't I use the M1-M4 ports instead of the H3 port? Based on what I was reading, it looks like the Hx Ports could be used CATV and/or MoCA.

Either way, Thank you. I will purchase this and some terminators and plan some time to swap it all out and see what happens.
 

krkaufman

Senior Member
I like this splitter you linked. For the MoCA Adapters (the top 3), wouldn't I use the M1-M4 ports instead of the H3 port? Based on what I was reading, it looks like the Hx Ports could be used CATV and/or MoCA.

Either way, Thank you. I will purchase this and some terminators and plan some time to swap it all out and see what happens.
What's critical is that you connect the cable modem run to the low-loss port, H1.

Beyond that, it shouldn't matter to which ports you connect your MoCA-only coax runs. The loss at MoCA frequencies should be the same between all output ports, so your MoCA-only coax runs can be connected to any of H2-H3 or M1-M4. Were you to have some other components that required the raw cable signal, they would, of course, need to attach via H2 or H3.
 

krkaufman

Senior Member
Not sure where this ended-up, but another option for improving the signal strength to the cable modem might be to use a tap (directional coupler) rather than a 2-way splitter at the modem location, to lessen the signal loss enroute to the modem.

e.g.
tap.jpg
 

Mark070

Regular Contributor
To update what has happend..

I ordered and received the Amphenol splitter board and the terminators. I have not had time to hook it up and see what the cable modem looks like. I am planning on getting to it this weekend.

I have no idea which of those tap's I would get if I needed one of those as well.
 

krkaufman

Senior Member
Hopefully the Amphenol hybrid splitter is sufficient, so just as FYI...

I have no idea which of those tap's I would get if I needed one of those as well.
Re: Taps ... A simple 2-way splitter evenly splits the coax signal strength between the 2 outputs, with commensurate, but equal, loss.

A tap (directional coupler), on the other hand, unevenly splits the signal between the "Out" and "Tap" ports, with the "Tap" port being attenuated by the labeled loss (-6 dB, -12 dB, etc.) and the "Out" port suffering a lesser degree of loss than it would via a simple split, inversely proportional to the tap port's loss. (i.e. The greater the loss on the "Tap" port, the less loss via the "Out" port.)

So, you could conserve some signal strength enroute to the modem by using a tap/directional coupler, but you'd need to keep the MoCA network's budget loss numbers (57 dB max) in mind when choosing how much attenuation the MoCA adapter's line could accommodate.

Per the instructional video, the output port isolation of the Amphenol hybrid splitter is up to 28 dB*, so that leaves just under 30 dB for the coax lengths and the 2-way split -- not that you'd want to play it that close.


* 16 dB b/w MoCA-only ports, up to 28 dB b/w a hybrid and any other port.
 
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krkaufman

Senior Member
Revisiting this prior question of your's, on having watched the instructional video for the Amphenol hybrid splitter (DOCSIS passive)...
I like this splitter you linked. For the MoCA Adapters (the top 3), wouldn't I use the M1-M4 ports instead of the H3 port?
Given the port isolation losses cited in the video...
16 dB b/w MoCA-only ports, up to 28 dB b/w a hybrid and any other port.
DOCSIS passive port isolation.jpg

... YES, you should use the MoCA-only ports for your MoCA adapter-only locations, and cap the unused hybrid ports, H2 & H3.
 

Mark070

Regular Contributor
ok, got some time today to rip it all apart, relabel all the cable lines and add in the Amphenol splitter. I also have a splitter to split the line from the wall, to the MoCA adapter and the Cable Modem. This is the new picture, which, I think seems ok. I will run it this way for a bit and see if everything is fine

EDIT: I have been watching the Modem to see if everything is holding, and it looks like it is. Thank you (in advance) for helping figure this out with me, much appreciated. Hopefully, I am not celebrating too early. Side note, Ubiquity looks like is releasing 1.8.3 firmware for my Dream Machine (base), so ... with that, I am hoping for a set it and forget it setup.
 

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