Did you end up getting a solution on this? Im having similar problems with the switch to DOCSIS 3.1 and have been hunting down similar sounding problems.
Hi Adam1089, I'd be happy to help you with your connectivity issues as well. For further assistance please send me a private message with your full name by clicking on my name (ComcastAmir) and then click "Send a message".
@Adam1089 Nope, I've still been unable to find a resolution for this even after 4 tech visits. Each time they come, they can't find anything wrong. In my most recent visit last Sunday, they claimed they put my modem on a 24 hour monitor to gather more information about the problem. However, they are either still actively gathering information and haven't had their maintenance teams address it or they stopped the monitor and forgot about me. As of late, I've noticed the signal level across all the channels including OFDM stays in spec signal wise, but I still get a significant amount of uncorrected codewords across all channels, more so with the higher frequencies above 630 MHz or so. What's odd is it seems to happen the most often between 8PM and 11PM EST. I suspect it happens late at night when I'm sleeping as well because I will see where my internet applications disconnected at some point during the night and just never reconnected or timed out (IE Steam friends list). I also don't understand why I'm not seeing any T3 timeouts with this and why it suddenly started happening at the end of April when I've had the Gigabit service that utilizes DOCSIS 3.1 since last September. I've also been on the same cable connection at this address with no signficant hardware infrastructure changes locally the last 5 years without an issue on DOCSIS 3.0.
I can investigate your issues deeper to see if I'm able to help find a resolution to your issues. I can check your signals and node and if needed communicate with your local line techs or maintenance team if needed. Please send me a private message by clicking on my name, "ComcastChe" then click send a message. In the body of this message please verify your first and last name.
@Adam1089 While I'm waiting for a reply from my PM to @ComcastChe I think we are on to something with regards to this being related to DOCSIS 3.1. I've been having the issue this morning as well, which is unusual since it happens in the evening most of the time. However, just like my original screenshots showed, there is a pretty large discrepency in the SNR on the OFDM channel. When it happens, the SNR drops to at or below 30 dB, which is out of spec and can cause issues. Alternatively, something upstream from me will flood every bonded channel I have with errors to the point my speed gets stuck at 35 Mbps until I reboot the modem to clear them up. The OFDM channel is new to DOCSIS 3.1 and a main feature of it. In addition, I've been noticing quite a few errors across all bonded channels, obviously much higher on the OFDM channel, and more so during that 8PM-11PM EST time frame. My guess? Either somebody who also has Gigabit tier with DOCSIS 3.1 is injecting noise/power back into the line for the whole area when they frequently use their service at that time or they have an issue on the CMTS sending out a lot of errors. I'm leaning more towards the former due to the evening timing when a lot of people are using the service and it happening right now on a weekend when people are off. It also explains why the last 4 tech visits of mine haven't found anything wrong on my line signal wise. My hunch is if I downgrade back to a lower speed tier that uses DOCSIS 3.0, I might be able to avoid this altogether. The reason I think this? I had the noise/power issue last night during the normal time frame and out of curiosity switched over to WiFi using one of my neighbor's Xfinity open hotspots. These Xfinity hotspots are available on Xfinity provided equipment such as their 2 in 1 devices and you just log into its portal with your Xfinity account. Low and behold, it stayed rock solid the entire duration I was on it until I switched back to my own cable modem once the noise/power issue cleared up. Presumably, if they were also on DOCSIS 3.1, they should have been having issues as well at the same time as me, but they weren't. The only conclusion I can think of since my own line and equipment isn't the issue is that they are still using DOCSIS 3.0 on the Blast! or Extreme Pro tier and aren't utilizing the OFDM channel, so by association aren't susceptible to issues on it.
I've had the chance to review your private message and check your signals. I believe your issues are due to the node in your area. Based on what I see on my end, there may be an issue there, causing the symptoms you are reporting. This would explain why the techs who have come out aren't able to find a problem at your home. I'd like to see if I can get in contact with someone from your local maintenance team. I will reply to your private message with more details on how I can get this ball rolling. Chat with you soon.
Hey, @DeityZero thanks for the followup to my question.
I'm seeing almost the same issue over here, but with variances that I won't clog your thread up with. I let my modem stay up as long as possible to see how many uncorrectables I was getting and it was over 5 million (minimum) on each channel before the modem's webpage stopped responding.
Now my Xfinity account page says that there should be scheduled maintenance in my area soon. Hopefully, it's something that is related to my problems.
Hope that you get your issue cleared up! Please respond with whatever you find out.
@Adam1089 So far, @ComcastChe has been very helpful with checking my signal and we have narrowed it down to my local node being the primary culprit. My local maintenance team has also been monitoring the issue since the last tech visit on 5/22 and are investigating it, but no resolution on their end thus far. It's beyond frustrating because I'm paying $90 a month for a service I can't even use the majority of the time right now while this local maintenance team gets to take their time fixing this at their leisure.
I just wanted to let you know I've provided an update about the issues at your node. As for your monthly rate and the fact that your services aren't working as expected, I am going to make sure you are compensated for the amount of time your services haven't been working. More details about that have been provided in our private message as well. Chat with you soon!
@Adam1089 I just wanted to keep you up to date on my progress just in case any of it helps you as well.
As of today, I'm still having the issue, but to a much lesser extent. I had finally managed to get a maintenance ticket open after they presumably saw something with the signal power during 24/7 monitoring back on 5/22 and they finally closed it last Thursday. To their credit, the disconnects due to the low signal power on the OFDM channel (678 MHz) is gone. However, it seems to have evolved into another problem in that I'm still getting the disconnects, but only for a few seconds once a night. When I check the cable modem around the time this happens, the OFDM channel is hovering around 18-20 dBmV while the rest of my 32 channels are sitting around 7-10 dBmV like they always do. My SNR has good numbers and has a clear signal across the board even on OFDM and my modem never resets or times out.
Long story short, ComcastChe checked my signal level during the time the maintenance ticket was open and he believes it was related to the local node. The maintenance team addressed the low signal power issue on the OFDM channel I'm assuming, but now the signal level goes the opposite direction out of spec and cause the issue to happen that way, albeit to a lesser extent. Hopefully that makes sense. I'm hoping they can just reopen the maintenance ticket with the info I provided ComcastChe this morning.
@Adam1089 It's been a little while since I last updated you, so I wanted to give you some more feedback. I had another scheduled tech visit today after we thought the issue was resolved after not experiencing any major issue for a couple of weeks, only for it to return worse than ever. I'm glad I did because I finally got one of the better, more thorough local techs in the area that found the culprit. My Netgear CM1000 Gigabit tier provisioned modem was locking onto a DOCSIS 3.0 channel for service correctly (in my case usually 603 MHz), but OFDM/DOCSIS 3.1 is locking onto an analog only frequency range (in my case 678 Mhz but it could be anything between 675-681 Mhz) for my downstream traffic. This was why I would lose connectivity from errant line noise, but my modem wouldn't show any visible signs of issues.
Long story short, basically I was allowed to upgrade to the Gigabit/DOCSIS 3.1 tier last year and provisioned correctly for it, but my local infrastructure around my apartment and nearby wasn't prepared for it yet. The local tech opened up a maintenance ticket for it and they should hopefully be addressing this in the next 3 days, give or take because of July 4th and the weekend. If I was you and you still don't have a resolution for this, check two things: 1) What channel/RF frequency your modem itself is locking onto (usually near the top of the modem status page) and 2) What channel/RF frequency your OFDM/DOCSIS 3.1 is locked onto. There is usually a specific range Xfinity will use in your area for DOCSIS, with DOCSIS 3.1 using the higher frequencies. If OFDM is locked onto a frequency that seems way out of proportion than what you are seeing across all the DOCSIS 3.0 bonded channels, let the tech know.