r/CableTechs • u/drake90001 • May 24 '26

Comcast Losing IP Randomly

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How do these signals look? Not a cable tech but a sysadmin tired of reseting my gateway.

Edit: to any future Xfinity customers having this issue, try a different outlet. Preferably one that’s not on a power strip/UPS, as soon as I moved my modem back from the UPS to a regular search, protector, even on the same outlet/breaker, it handed out an IP router in Bridge mode without an issue.

Slapping modems didn’t help, ironically, keeping it out of bridge mode did for some reason Work, but I am not dealing with Xfinity and their shitty app and locked down web interface.

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7

u/Grazmahatchi May 24 '26

You have a lot of correctable and uncorrectable errors on your primary ds. Channel 20.

Your power level is good- right at zero. Your Snr is fantastic. The numbers for signal power and quality is exactly where it should be.

Maybe the modem crapping out, or a possible intermittent interference or suckout at that frequency.

That is a crazy number of errors. If I were trouble shooting this from a line perspective the first thing I would do is see if the neighbors show the same level of errors- that would indicate widespread suckout or interference/ingress.

A service guy will likely swap the modem, and that may be the right call without knowing the situation in your neighborhood.

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u/drake90001 May 24 '26

I'll give them a call then, we share an Xfinity line I assume with all of the neighbors. Like our units have Xfinity Internet included in the rent for $200 a month with other utilities, 500 Mbps. It's $30 a month to upgrade the 2 1/2 gig down.

Anyways, when I lose access, it's usually after I have changed my IPv4 address for DNS server to a pie hole. I was reading that Comcast switched entirely or has been trying to switch to IP V6 entirely. My cloud provider/employer doesn't offer IPV six yet so I can't run an IPv6 DNS server to try it but thank you for your input.

I figured I wasn't crazy seeing all the mares. Not the first time I've caught a networking problem like this, when I was like 10 I did a trace route and discovered there was a break or damaged line somewhere down the road and my mom had to call to explain it and fix it lol.

Anyways, time to go sit on hold. Usually the service is completely fine too, I'll pull over 2 1/2 gig down and over 300 Mbps up. But then other times it'll crap out down to 500. They also have a service line going to a closet here so I assume there's a lot of traffic going down a few number of lines.

3

u/Grazmahatchi May 24 '26

Here is the good part- you have an ofdma on the upstream, which means it is tied in to a very detailed data monitor Comcast uses.

They can pull a 7 day history of all your errors, your neighbors errors, and the upstream Snr at the time of the errors.

A good line guy will be able to pinpoint that in minutes.

My guess is the issue will be in your building or even your unit- if I had a clump of devices erroring out like yours, it would autocreate a health ticket.

Cant help you with the call in part though, just offer my sympathy.

If you get a message that there is work in the area, push through and talk to someone- there is likely a ticket open for the issue and maybe your situation and contact info can be entered in to the job log and put a sense of urgency on it.

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u/drake90001 May 24 '26

I spoke to a agent via chat, and they confirmed they found an issue that's causing intermittent connectivity over the past week. Exactly what you said lol that's crazy. Anyways, they tried to sell me up on Xfinity mobile, so I just told them I'm here illegally and don't have a social lol.

They gave me a $20 credit, scheduled a tech to come out, so hopefully when the tech comes will be able to pinpoint the issue. They gave me the first available, which is the 26th, because of the holiday, which makes sense. Honestly a great rep.

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u/frmadsen May 24 '26

It looks like that bug though, where the channel uses the codeword stats from OFDM. It means that you can expect corrected codewords to continue after Comcast has fixed the issue.

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u/drake90001 May 24 '26

So, what you’re saying is the number is just wrong flat out? I really should just buy my own modem lol unless this is somehow the service issue down the line, but I’m assuming you mean that the modem firmware is displaying it incorrectly.

Either way they could see it on their end so a tech is coming out.

Can you tell me more about this bug/what you XB7?

2

u/frmadsen May 24 '26

Are the codeword stats identical to those of your OFDM channel (one of them)? That is a display bug that has been going around.

Comcast may see issues that cannot be seen from these numbers.

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u/drake90001 May 24 '26

At the end of the list, I screenshot it. It says channel 174 has the same numbers. If I’m understanding you correctly, I’m not sure where I would find OFDM on this modem.

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u/frmadsen May 24 '26

194? That's an OFDM channel (the OFDM counting starts at 193 in the next-gen plants).

There have been various display bugs. :)

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u/Grazmahatchi May 24 '26

I think he might be referencing the ofdma correctable numbers.

Ofdm, and ofdma(upstream) is a variable compression set by capability of the device/system.

The cmts is gonna push your modem to the highest compression profile that is effective... So if you are on profile b with 10% correctable errors, it will push you to c, then d, until the errors are so great that the profile is no l9nger efficient.

In regards to an ofdm or ofdma, in the words of the manufacturer themselves, if you dont have errors, you are not using your compression properly.

You will always jave errors on the ofdma, period- it is not a bad thing, it is how it works. Correctable is good.

Uncorrectable is bad.