How to Troubleshoot Intermittent Internet Dropouts?

[Qs Laptop]

This is super annoying. I've got Comcast internet and TV service. I've got a Motorola Surfboard SB6121 modem, which I purchased several (many?) years ago. I believe we have Comcast's 150 Mbps speed option.

In the past several weeks I've suffered intermittent internet dropouts typically lasting between 1 to 3 minutes. When this happens my streaming TV service will stop, my computer and phone(s) will indicate no internet connection, and when I check the indicator lights on the front panel of the modem it confirms that I'm not connected to the internet. Sometimes, though rarely, the cable TV service will also go out along with the internet.

These dropouts occur 1 to 3 times daily. Pretty consistent, as I can't remember the last day I had full internet connection for the entire time I was wanting to be connected. There is no repeatable time of day that it happens.

Oddly, two times in the past week I was streaming content and when there was a loud explosion on screen the internet disconnected immediately afterwards. The first time this happened I thought it was a coincidence, but the second time? Also, when I mentioned this to my son he reminded me that this phenomena happened to him when he was still living here.

Before I call Comcast and have them read their dumb script--"Did you reboot your modem and router?" "You need to replace your modem" etc. etc.--I'm wondering if there is anything I can do to absolutely rule out my modem as the possible problem? Any troubleshooting techniques I can try out before I call Comcast?

I suspect the coaxial cable running from the junction box in my backyard and into my house could be the culprit. This problem has occurred before, about 8-9 years ago and the fix was to replace the underground coaxial cable.

[gauss]

Can you buy a new modem (with appropriate return privileges) at the local big box store to see if this indeed fixes the problem or not?

I have done this with flaky older Wifi/routers in the past to quickly isolate the problem.


-gauss

[Qs Laptop]

Quote:

Originally Posted by gauss Can you buy a new modem (with appropriate return privileges) at the local big box store to see if this indeed fixes the problem or not? I have done this with flaky older Wifi/routers in the past to quickly isolate the problem. -gauss

Yes, that's a possibility. I was hoping someone could tell me if there was an error log for the modem I could somehow access and learn something from it. Or some other technique to quickly implement the next time there is a dropout.

[Texas Proud]

I get some dropouts on Comcast at times... but do not get them as often as you...


Here is one thing I learned trying to fix a problem with a smart sprinkle controller... it keep dropping and had problem getting reconnected.. they suggested that I go in and put the device as 'home'... if a device is not listed as home it is considered as a guest and they said that Comcast will drop guests at times and they have to log back in...


It seems to have worked most of the times for me... the controller does drop but not nearly as often and it gets back online by itself...

[MichaelB]

Quote:

Originally Posted by gauss Can you buy a new modem (with appropriate return privileges) at the local big box store to see if this indeed fixes the problem or not? I have done this with flaky older Wifi/routers in the past to quickly isolate the problem. -gauss

+1. I had internet dropouts 4-5 times per day for half a year, and none since changing routers. The old router was not old, just bad.

To avoid potential issues with Comcast and also to help avoid being billed for their support, all the internal connections should first be tested. The modem, the router, the cable connecting the modem to the external source.

[Aerides]

Run a ping on a -t.

from the command prompt (put CMD in your windows search bar) and then ping -t www[dot]comcast[dot]net but obv just the actual url not brackets - didn't want to leave a link to them here.

A normal ping test will do 4 hits and then end, a -t makes it perpetual. And no, the increased "traffic" from this background continuous ping will not impede your other performance.

If you have no drops it's something else. If you are seeing drops or massive spikes in the ms times that match with your performance degradation, it's in the network somewhere.

If your cable terminates on an external box on your house, and you have a laptop and an ethernet cable, you can go outside and do this there - that would eliminate (or isolate) that the problem is inside the house.

Then it's process of elimination from there.

If you are getting more than one drop per page, it's them.

We had tremendous drops like this that were shown to be external via the outside test like this. It took two months of arguing, each time some dude would come to our house and try to say it was our modem, have us reboot, stupid stuff. It was the first and only time I've ever heard my husband raise his voice and curse at anyone. And he was right to do it.

Eventually, comcast had to change out a board on the termination point nearest our house that was overheating.

good luck - hope it's your modem or router, that's the easy fix!

eta: added a pic of a bad result - this is what we had when we were having our issues. Imagine gaming with this...

[Z3Dreamer]

The ping test sounds good. New routers that do all most want are under $100. You say your router is old. Maybe replace. No one has mentioned reading the logs in your router to see about the drop offs. Or did they and I missed it?

[Qs Laptop]

The router and modem are separate units. If the modem's front panel indicator lights are showing no internet connection I don't think the router even enters into the equation since it is "downstream" from the modem.

[steelyman]

Are there any other options (Internet providers) in your area beside Comcast?

This situation does sound extremely annoying.

[Car-Guy]

I was having dropouts too on all my wireless (802.11) connections for the past year or so... No real detectable pattern. Sometime it happened a couple of times a day, and sometime "days would go by" without a hit. I'd check the modem and all "seemed" ok... I'd usually had to reset the modem to recover my DSL Internet service when this happend... (POTS always kept working)

Anyway, I recently bought a new PC and connected it (via wireless too) and shutdown my old one... You guessed it, I haven't had a dropout since.

Coincidence? Or was there a problem with my old PC's wireless connection that was blowing up my modem.... Never would have guessed that one.

[RetiredAndLovingIt]

Following, I'm having the same issue but I'm a Spectrum customer.
Sometimes when it happens there's a red light on the router and if so then unplugging both for 20 seconds or so will fix it. The blue online light on the modem is fine. My internet was out for 6 hours in the middle of the night 2 days ago and the simple reboot fixed it so is the issue modem or router? I have been meaning to call Spectrum and ask them to check their trouble logs and see if they can troubleshoot my modem before I buy a new router.
I also have the issue of the modem dropping for a minute or 2 and coming back on again by itself and that also happens 3-4 times a day usually when I'm live streaming. I run to my office to check the router lights and they are all fine so still connected.
When I had a similar issue years ago and was using my own surfboard modem Spectrum said it was no longer supported and sent me a new one and since they no longer charge us for the modems I was happy to let them do that. That solved the problem at the time and a few years later I upgraded the router so it's only about three years old now.

[Qs Laptop]

Quote:

Originally Posted by Aerides Run a ping on a -t. from the command prompt (put CMD in your windows search bar) and then ping -t www[dot]comcast[dot]net but obv just the actual url not brackets - didn't want to leave a link to them here. A normal ping test will do 4 hits and then end, a -t makes it perpetual. And no, the increased "traffic" from this background continuous ping will not impede your other performance.

Am running the ping test right now, it's been about 20 minutes. So far, there was one time out early in the process, then a double time out maybe 10 minutes later but otherwise just continual repetitious ping times of (mostly) between 23ms and 28ms.

Ping-Test-1-091922.jpg

Ping-Test-2-091922.jpg

Any thoughts on these ping times?


I presume I keep this running until I get a dropout and then toggle over to the command window running the ping test and take note of the ping time readout?

Quote:

If you have no drops it's something else. If you are seeing drops or massive spikes in the ms times that match with your performance degradation, it's in the network somewhere. If your cable terminates on an external box on your house, and you have a laptop and an ethernet cable, you can go outside and do this there - that would eliminate (or isolate) that the problem is inside the house. Then it's process of elimination from there. If you are getting more than one drop per page, it's them. We had tremendous drops like this that were shown to be external via the outside test like this. It took two months of arguing, each time some dude would come to our house and try to say it was our modem, have us reboot, stupid stuff. It was the first and only time I've ever heard my husband raise his voice and curse at anyone. And he was right to do it. Eventually, comcast had to change out a board on the termination point nearest our house that was overheating. good luck - hope it's your modem or router, that's the easy fix! eta: added a pic of a bad result - this is what we had when we were having our issues. Imagine gaming with this...

Wow. That would not be good!

[Qs Laptop]

Quote:

Originally Posted by steelyman Are there any other options (Internet providers) in your area beside Comcast? This situation does sound extremely annoying.

There is CenturyLink (formerly Qwest) but the fastest service available at my address is 80 Mbps.

[Aerides]

Quote:

Originally Posted by Qs Laptop Any thoughts on these ping times? I presume I keep this running until I get a dropout and then toggle over to the command window running the ping test and take note of the ping time readout?

Exactly, if you are not having issues at this moment, then that ping is reasonably healthy. That's why you can keep it running in the background, so that when you see issues in performance you can look at the pings in real time.

[Qs Laptop]

Quote:

Originally Posted by Car-Guy I was having dropouts too on all my wireless (802.11) connections for the past year or so... No real detectable pattern. Sometime it happened a couple of times a day, and sometime "days would go by" without a hit. I'd check the modem and all "seemed" ok... I'd usually had to reset the modem to recover my DSL Internet service when this happend... (POTS always kept working) Anyway, I recently bought a new PC and connected it (via wireless too) and shutdown my old one... You guessed it, I haven't had a dropout since. Coincidence? Or was there a problem with my old PC's wireless connection that was blowing up my modem.... Never would have guessed that one.

I'm glad you got it fixed, but it must be kind of frustrating not knowing for sure where the problem originated.

My primary PC is connected via ethernet directly to the router.

[target2019]

My 1st guess is usually my best. You're having coax or fibre connection problems.

The coax connections at the curb, entry, and modem should be checked.

I have the ARRIS SB6183 cable modem, and use that with a newer Netgear router. SB6183 default address is 192.168.100.1. Your SB6181 may be different. It will be a little challenging to get to 192.168.100.1 from your subnet 192.168.1.x.

The modem does have logs which you can inspect.

[Qs Laptop]

Quote:

Originally Posted by Aerides Exactly, if you are not having issues at this moment, then that ping is reasonably healthy. That's why you can keep it running in the background, so that when you see issues in performance you can look at the pings in real time.

Got it.

I just scrolled through the past 10 minutes or so and there was one "round trip" that took 1216 ms otherwise the usual 23-29 ms ping time.

[steelyman]

Quote:

Originally Posted by Qs Laptop There is CenturyLink (formerly Qwest) but the fastest service available at my address is 80 Mbps.

Unacceptable.

I’d been experiencing similar problems here with Spectrum (cable) and before that in the midwest with Comcast (also cable).

The only thing that seems to have set it right was switching to fiber. I guess many old coax cable systems are deteriorating with time and lack of maintenance.

[Qs Laptop]

Quote:

Originally Posted by target2019 My 1st guess is usually my best. You're having coax or fibre connection problems. The coax connections at the curb, entry, and modem should be checked.

Do you suggest disconnecting them and reconnecting? Or simply making sure they are tightly connected without disconnecting?

Quote:

I have the ARRIS SB6183 cable modem, and use that with a newer Netgear router. SB6183 default address is 192.168.100.1. Your SB6181 may be different. It will be a little challenging to get to 192.168.100.1 from your subnet 192.168.1.x. The modem does have logs which you can inspect.

I can get into 192.168.100.1 easy enough. I can see the error logs. Thank you.

Since booting up my computer this morning I see 20 errors varying from:
5 - Warning
4 - Error
3 - Critical

I don't see a way to view logs from previous days, only the current day. The last log entry happened 62 minutes ago, prior to my running the ping test and was:

Received Response to Broadcast Maintenance Request, But no Unicast Maintenance opportunities received - T4 time out;CM-MAC=94:**:**:**:**:**;CMTS-MAC=00:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;

All other log entries happened in the first 27 minutes after booting up my computer.

[Qs Laptop]

Quote:

Originally Posted by steelyman Unacceptable. I’d been experiencing similar problems here with Spectrum (cable) and before that in the midwest with Comcast (also cable). The only thing that seems to have set it right was switching to fiber. I guess many old coax cable systems are deteriorating with time and lack of maintenance.

CenturyLink does have fiber, just not in my neighborhood.