Internet drops only when gaming.

[Vunter]

My ISP: Comcast - speeds 250/15
Cable Modem Bridged
Router: Asus RT-AC3100

During the process of troubleshooting I have done tons of research of possible culprits. I thought maybe it was DNS issue so I played around with using ISP DNS, Google DNS, and Cloudflare DNS. Issue still persisted; then I thought maybe it was a bufferbloat thing so I turned on QOS and bandwidth limiter to 90%. I then thought it was a UPNP thing and disabled that and manually port forwared everything that needed it; that didnt work so I reverted back to default UPNP settings. So I've had an intermittent connection for many months and called comcast numerous times to fix the issue. They have since replaced my modem a handful of times and completelty rewired my house twice. I have also replaced all the ethernet cables in the house.

Since the last tech came out I no longer have an insane amount of disonnects, but now it will only drop when I game on my PS4 or when I game on my PC. What happens is the entire network losses connectivity for 3 - 5 seconds. I can browse the internet all day, stream youtube all day, stream twitch all day, I basically can do just about everything except I can like clockwork get the issue to happen by trying to game on the PS4 or PC.

At this point I don't think it is a modem thing, but then again many of the comcast rented modems are running older firmware versions so I'm wondering if it would be worth buying my own cable modem; then again I'm not entirely sure this will fix the issue. The other thought I had was switching back to my old Tmobile AC1900 Router. My disconnects existed back when I had the AC1900 router and I bought the AC3100 just to rule out the router being an issue. I have also thought maybe it is an IPV6 thing and thought about disabling IPV6, but don't really know if IPV6 is the issue.

Since the issue persists regardless if I have QOS on or not I left QOS on since my network has been more stable with it on. I'm at a loss really to the point that I no longer game on comcast and I tether my tmobile phone when I game because it's just exhausting trying to figure out what the issue is.

Anyone have any ideas?

 

[Vunter]

Here is router log; i removed ip's. I took two screen shots instead since i couldnt figure out how to submit them without triggering the site security. Based on these logs I'm assuming the issue still lies with comcast and or my cable modem since the log says ISP DHCP not working and the WAN is dropped.

 

[coxhaus]

There is suppose to be some kind of problem with modems that contain the puma 6 chipset. Whether this is your problem I have no idea. You need to google gaming and puma 6 chipset. The cable companies typically give you these modems.

 

[ColinTaylor]

The significant entries in your log are:

Aug 16 02:31:19 WAN_Connection: Ethernet link down
Aug 16 02:31:24 WAN_Connection: Ethernet link up

This indicates that the router lost the physical connection to the cable modem. I'm assuming it wasn't you rebooting your equipment?

Check the logs on the cable modem for clues.

 

[Vunter]

The significant entries in your log are:

Aug 16 02:31:19 WAN_Connection: Ethernet link down
Aug 16 02:31:24 WAN_Connection: Ethernet link up

This indicates that the router lost the physical connection to the cable modem. I'm assuming it wasn't you rebooting your equipment?

Check the logs on the cable modem for clues.

So last night I contacted comcast because the logs are empty on the modem and I have been trying to get them to fix that, but it hasn't been happening. Anyways as usual they refreshed the signal to the modem and when the internet came back up as a test I fired up a game and thats when the Router lost the connection.

There is suppose to be some kind of problem with modems that contain the puma 6 chipset. Whether this is your problem I have no idea. You need to google gaming and puma 6 chipset. The cable companies typically give you these modems.

The cable modem I have is the Technicolor CGM4140COM and upon googling it doesn't appear to have that chipset.

 

[ColinTaylor]

So last night I contacted comcast because the logs are empty on the modem and I have been trying to get them to fix that, but it hasn't been happening. Anyways as usual they refreshed the signal to the modem and when the internet came back up as a test I fired up a game and thats when the Router lost the connection.

So just to be clear, the disconnection at 02:31:19 was you playing a game and not comcast resetting the modem? That would still strongly indicate that the modem rebooted itself.

 

[Vunter]

So just to be clear, the disconnection at 02:31:19 was you playing a game and not comcast resetting the modem? That would still strongly indicate that the modem rebooted itself.

Thats correct. Comcast rebooted the modem and then once the modem and my network came back up I loaded my game and then thats when the Router lost its connection; you can see from the router logs that the router regained the connection after about 20-30 seconds.

 

[ColinTaylor]

You said you had the same problem with your previous router. I suppose it's possible you had (have?) multiple different problems.

I see there's a message in the log about dual-wan. Probably irrelevant but are you using dual-wan?

 

[Vunter]

You said you had the same problem with your previous router. I suppose it's possible you had (have?) multiple different problems.

I see there's a message in the log about dual-wan. Probably irrelevant but are you using dual-wan?

Yeah I have had multiple issues with my connection spanning many months. Before this latest issue I was getting hundreds of disonnects a day that spanned seconds to many minutes. Had multiple techs come out and one tech replaced all the coax ends saying that was the culprit. I will admit the connection did get better but intermittent drops still occured. Then a couple of weeks later another tech came out and completely pulled the coax and put new coax in. Since then no issues at all except when I try to game online. I don't use Dual-Wan so I have that feature disabled. I doubt it will fix the issue but later this afternoon I am going to an xfiinty store to have the modem replaced again; i did some googling and turns out when the modem doesnt display the logs it is a glitch in the firmware so maybe this specific modem is bad. Worst case scenario im back where I started and can rule out the modem again.

 

[ColinTaylor]

Being able to see the modem log will be a big help, even if it's just to eliminate the modem as the source of the problem.

I had a look for the source of the "DHCP did not function" message. It appears to come from the watchdog process (duh!). The code is too complex for me to really follow; but the fact that it appears before the "Ethernet link down" message might indicate the router is deliberately forcing the interface down and up. It appears to do this when it thinks it's lost connection to the upstream device. If that's the case then we're back where we started. The router thinks it's lost connection to the modem. The question is whether that's actually true or not.

 

[Vunter]

Being able to see the modem log will be a big help, even if it's just to eliminate the modem as the source of the problem.

I had a look for the source of the "DHCP did not function" message. It appears to come from the watchdog process (duh!). The code is too complex for me to really follow; but the fact that it appears before the "Ethernet link down" message might indicate the router is deliberately forcing the interface down and up. It appears to do this when it thinks it's lost connection to the upstream device. If that's the case then we're back where we started. The router thinks it's lost connection to the modem. The question is whether that's actually true or not.

Yeah I too really wish I could see the cable modem logs. Turns out lots of Comcast customers are reporting this issue which kind of makes me think it's on purpose, I know I'm kinda wearing a tin foil hat. Yeah I'm not entirely sure either.

 

[Vunter]

So according to other threads on these forums some people fixed their drops by disabling dhcp first and then enabling bridge mode. I guess it's worth trying, disabling bridge mode, disable dhcp, then enable bridge again.

 

[ColinTaylor]

So according to other threads on these forums some people fixed their drops by disabling dhcp first and then enabling bridge mode. I guess it's worth trying, disabling bridge mode, disable dhcp, then enable bridge again.

It's worth a try. Although I'm not sure I follow how you'd get a WAN IP address.

What I could imagine might work would be to have everything setup and working as normal. Make a note of your WAN IP address, subnet mask, gateway and DNS servers. Then switch your router's WAN configuration from "Automatic IP" to "Static IP" and enter the values you recorded earlier. Maybe that might work.

 

[Vunter]

It's worth a try. Although I'm not sure I follow how you'd get a WAN IP address.

What I could imagine might work would be to have everything setup and working as normal. Make a note of your WAN IP address, subnet mask, gateway and DNS servers. Then switch you router's WAN configuration from "Automatic IP" to "Static IP" and enter the values you recorded earlier. Maybe that might work.

I meant disable the dhcp on the cable modem.

 

[ColinTaylor]

I meant disable the dhcp on the cable modem.

Ah, OK.

 

[coxhaus]

Why not look a your cable modem log. type 192.168.100.1 into a browser, it should bring up your modem's log.

 

[Vunter]

Ah, OK.

Another thing people said to try was switching query frequency from aggressive to normal, however I remeber reading a merlin post where he says comcast users should stay with aggressive.

 

[Vunter]

Why not look a your cable modem log. type 192.168.100.1 into a browser, it should bring up your modem's log.

I can't look at the cable modem logs because they are empty. When I googled this, it turns out other Comcast customers report the same issue of having empty modem logs

 

[coxhaus]

I can't look at the cable modem logs because they are empty. When I googled this, it turns out other Comcast customers report the same issue of having empty modem logs

It works with Spectrum and my SB200 modem.

 

[Vunter]

It works with Spectrum and my SB200 modem.

Yeah it's suppose to work, what im saying is when I view the modem logs they are empty. They're three log sections on the modem: system, event, and firewall. The only logs that populate are when I login and out.

I called Comcast this afternoon and tier 2 support confirmed that their firmware they provision to the routers have glitch that is preventing logs from appearing correctly. When I get him tonight we shall see if the cable modem replacenent works, I doubt it though.