Question Is my modem bad? Or is Xfinity the problem? Modem screenshots linked...

[pa5tabear]

I linked screenshots in this thread:

Internet cutting out... is it my modem or is it Xfinity? Screenshot of Surfboard SB6141 logs linked

These are my screenshots with a recent cutout between the 8:30-8:35 times. During that time I saw the LED lights on the modem turn off, then eventually come back on without me needing to turn off its power. I think this sort of thing has been happening a few times a day for the past few weeks...

forums.xfinity.com

Since I'm not renting an Xfinity modem, I'm worried they'll just blame my old SB6141 and tell me to rent from them.

Any ideas on how to test? Or should I just buy a new one since mine is 4+ years old?

 

[SamirD]

I don't think its your modem as I've seen this on both of my sb6190s whenever the isp is having signal issues.

I'll usually give them a few days to fix their issue, but after that I'll call them about it and ask for credits for the problem days until they fix it.

My 6190s are over 5 years old now and they're still working well. The arris sb line is quite solid so I highly doubt its your modem.

 

[pa5tabear]

I don't think its your modem as I've seen this on both of my sb6190s whenever the isp is having signal issues.

I'll usually give them a few days to fix their issue, but after that I'll call them about it and ask for credits for the problem days until they fix it.

My 6190s are over 5 years old now and they're still working well. The arris sb line is quite solid so I highly doubt its your modem.

Did they willingly credit you for the problem days?

I didn't have this many issues prior to mid-March. Which was when I moved to a new building, and also when quarantine started.

But I kinda don't think quarantine actually matters that much for a weekday night. Pretty sure everyone was already plugged into their streaming video.

Is Xfinity responsible for the connection all the way to my apartment, or can they blame the apartment building for bad cables/splitters/etc?

 

[Genx87]

I had issues with Mediacom 15 years ago. About every 12-18 months a filter would become faulty. Which caused the signal to become out of spec and the modem would drop packets or reset.

 

[SamirD]

Did they willingly credit you for the problem days?

I didn't have this many issues prior to mid-March. Which was when I moved to a new building, and also when quarantine started.

But I kinda don't think quarantine actually matters that much for a weekday night. Pretty sure everyone was already plugged into their streaming video.

Is Xfinity responsible for the connection all the way to my apartment, or can they blame the apartment building for bad cables/splitters/etc?

Yep, they usually do.

Xfinity is responsible all the way to your modem or their modem. Most apartment complexes will run their own wiring to the proper spec, and I'm not sure who's problem it is to fix or pay for after that point, but my guess is xifinity fixes it and bills the apartment complex if need be.

I'm almost 100% sure it's not your modem now if you weren't having problems until you moved buildings. If you didn't have someone from comcast come out for the install (you did the self-install/connected the modem and then followed the prompts), there could be a signal issue that was never addressed. So someone will have to come out and check on that.

 

[VirtualLarry]

Well, with that all said... there have been reports, including juicy pictures, of SB6121 and SB6141 modems, "going bad", bad brown leaky electrolytic caps, etc.

Those modems are old enough (even if you personally haven't owned your modem that long), based on date of mfg, that it may well be time to replace it.

Also, they are only 8x4 modems, so if you have anything above a 25Mbit/sec plan, you are doing yourself and your neighbors a disservice. Modems with "more channels" help to "spread the load, on the node".

I mean, it could be an internal wiring issue, filters, noise on the line, etc. too. You could check your modem stats, go to 192.168.100.1, and see if you can check from there.

Edit: I mean, when you say, the LEDs turn off on their own, and back on... are you referring to the DS/US LEDs, or the Power LED too? If the Power LED is going off, on it's own, it could well be the physical modem failing, or the power brick. If it's just the DS/US LEDs, retraining, but the Power LED stays steady or blinking regularly, then it's probably an ISP/wiring/signal issue, IMHO.

 

[SamirD]

Yeah, but OP didn't have any issues until they moved buildings so I don't think it is a modem issue and more of a signal issue.

As far as the lights--even the power can be reset remotely or by the unit itself as my 6190 will do that if there's no signal.

 

[mindless1]

Get an internet connectivity logger to accumulate evidence then contact the ISP to get someone out to troubleshoot. Odds are it is on their end, not your modem, but it is good to have the log in case the tech finds no problem at that time.

However you may be able to call 2nd tier support (have it escalated if necessary) and they can see if your modem has dropped off the network. Of course it has to stay offline long enough to last through the queue of getting to talk to a live person to check it.

 

[pa5tabear]

Get an internet connectivity logger to accumulate evidence then contact the ISP to get someone out to troubleshoot. Odds are it is on their end, not your modem, but it is good to have the log in case the tech finds no problem at that time.

However you may be able to call 2nd tier support (have it escalated if necessary) and they can see if your modem has dropped off the network. Of course it has to stay offline long enough to last through the queue of getting to talk to a live person to check it.

I screenshotted my modem logs a week ago, and just did so again today. I'm hoping this is enough for now.

I had a call with Xfinity support a few days ago and the guy seemed knowledgeable and didn't blame my modem. He said he didn't see any signs of issues specifically for my connection, but he disclosed that there'd be an multi-hour cutout in the area a few weeks ago and wondered if that had messed up the configuration for my modem going forward. He then sent a reset signal and said he thought I'd be fine.

...But I just had another cutout now, so I'm posting more modem logs on the Xfinity forum and will call them asking for more help, and also try swapping in a new and upgraded Arris modem I picked up from BestBuy yesterday.

 

[pa5tabear]

Well, with that all said... there have been reports, including juicy pictures, of SB6121 and SB6141 modems, "going bad", bad brown leaky electrolytic caps, etc.

Those modems are old enough (even if you personally haven't owned your modem that long), based on date of mfg, that it may well be time to replace it.

Also, they are only 8x4 modems, so if you have anything above a 25Mbit/sec plan, you are doing yourself and your neighbors a disservice. Modems with "more channels" help to "spread the load, on the node".

I mean, it could be an internal wiring issue, filters, noise on the line, etc. too. You could check your modem stats, go to 192.168.100.1, and see if you can check from there.

Edit: I mean, when you say, the LEDs turn off on their own, and back on... are you referring to the DS/US LEDs, or the Power LED too? If the Power LED is going off, on it's own, it could well be the physical modem failing, or the power brick. If it's just the DS/US LEDs, retraining, but the Power LED stays steady or blinking regularly, then it's probably an ISP/wiring/signal issue, IMHO.

Yup, I have a 75MBps plan. Why do I need more than 8x4? The specs say my SB6141 should do 343MBps.

And I did check the stats. Seemed fine. Here are some more from today.

Re LEDs, I've never seen the power LED go out. Just the DS/US, and whatever the other two are, and yup, the power LED stays steady. Those LED "retrainings" (I didn't know that's what it was until now, thanks!) match up with the Critical T3 and T4 timeout times in the log.

 

[SamirD]

You don't need more than an sb6141--unless xfinity no longer official supports it. Yep, the modem will 'retrain' aks 'resync' when it has signal issues or is sent a reset from the head-end.

 

[mindless1]

I literally meant use a logger app, not just screenshots. Screenshots mean little as a persuasion tool for the ISP, anyone can have their internet drop once in a great while. The logging shows a pattern of it being excessive, catching every case (past X # of seconds the logger is set to check) without your having to notice and manually document it every time it happens, 24/7.

8x4 is enough channels for a 75MB plan. More and more these days, the ISPs will cap the throughput of each channel, so you probably wouldn't get as much as 300Mb out of it, probably more like >120Mb is where you'd start seeing an improvement going with more channels.

Usually if a modem gets flaky, it doesn't just drop the signal only to pick it back up again without any further intervention. Really soon it would start crashing and need a reboot at least.

 

[pa5tabear]

Gotcha, well I might get the logger app going. And to everyone else, how frequent of timeouts are normal?

I installed the new SB6183 modem a week ago and in that time the built in Event Log shows only one T3/T4 timeout event, compared to probably 15+ in a week's timespan with the prior modem.

I'm not sure how to interpret that.

Seems like my personal Xfinity connection/wiring/configuration is not perfect and could maybe be improved once their technicians are doing in home service calls again? But that my older modem was also making the problem worse?

 

[mindless1]

There's no normal for timeout frequency. Ideally it would never happen but does happen to most people, perhaps more often than their realize if they don't check logs.

There are many links in the chain and equipment and cabling ages, seasons change with temperature and rain, and the one certain thing is they happen more often as the links degrade, until it gets bad enough that someone raises a fuss and the tech on-site can catch it happening.

 

[SamirD]

Gotcha, well I might get the logger app going. And to everyone else, how frequent of timeouts are normal?

I installed the new SB6183 modem a week ago and in that time the built in Event Log shows only one T3/T4 timeout event, compared to probably 15+ in a week's timespan with the prior modem.

I'm not sure how to interpret that.

Seems like my personal Xfinity connection/wiring/configuration is not perfect and could maybe be improved once their technicians are doing in home service calls again? But that my older modem was also making the problem worse?

I just checked and I had 2 timeouts on Fri, and one each on Tues and Weds and didn't even notice any issues with my service. I think yours should be working fine.

And if your service works fine, I would try swapping to your old modem and that will test your modem for issues too.

 

[aigomorla]

I installed the new SB6183 modem a week ago and in that time the built in Event Log shows only one T3/T4 timeout event, compared to probably 15+ in a week's timespan with the prior modem.

it means Xfinity probably grandfathered out your modem, and no longer will support it.
So all the old ones connected will somewhat work, but have issues like how your having now.

You need to make absolutely sure the modem you have is approved, otherwise it will fail validation, and you will have spotty internet.
This is one benefit in renting the modem, as you can always return it for a new fresh one which is pretty much guaranteed to work out of the box.

Lastly i would also try different DNS host servers and not use the Xfinity's and see if that helps a little, as people hammering the DNS servers can also cause spotty connection, especially now with more people at home due to COVID-19 on internet.

 

[mindless1]

^ There is no grandfathered out. There is grandfathered in, meaning that existing customers using a certain model already registered to their Xfinity account, will still be able to continue using it, but no new activations of that model would be allowed.

That is not "no longer support it", it is still fully supported and fully functional. They just refuse to let customers do a NEW installation from a logistics perspective, has nothing to do with the modem dropping the internet connection.

IF it gets online at all, it has downloaded the config file and is not going to drop the internet connection once grandfathered (which SB6141 doesn't even appear to be yet, unlike SB6121), at worst it would just be capped to some n-channel x per-channel bandwidth below the service tier the customer is paying for.

There is no such thing as failing validation and then intermittently dropping internet connectivity due to that. It would never have any internet connectivity, ever again on their system.

 

[SamirD]

This is one benefit in renting the modem, as you can always return it for a new fresh one which is pretty much guaranteed to work out of the box.

The problem with the xfinity/comcast provided units is that they have hidden ap's that hurt overall wireless bandwidth by creating more noise in the air. It was so bad at our old apartment that we ditched their unit and saw our wifi speeds return to normal. Plus, the rental fee is ridiculous now, something like $11 or $15/mo. A used modem will have an roi of just a few months.

 

[MtnMan]

The log just shows what happened, but not the why.

You need to look at the signal level and SNR on your modem. If the signal reaching your house is not what it should be, no modem will work without issues.

https://arris.secure.force.com/cons...Cable-Signal-Level/?l=en_US&fs=RelatedArticle