The tech came by and cut/replaced the coax connectors throughout the basement as well as in the box outside (several there, 4 room apt). Spent some time on the pole and then confirmed there was no longer a noise/ingress issue. Even picked up the cablebox I hadn't yet returned for the service I dropped previously.
I was still seeing lower speeds but no errors in the modem logs and full upstream locks- turned out to be something I'd tweaked with my router trying to figure out what was going on earlier. Reverted the router and everything is back to normal and better than it was before my problems began! Now I just need to swap out the 4x4 modem for the 16x4.
Big thanks to EG and KenF for the assistance.
... View more
I picked up a NETGEAR CM500 to test, as mentioned might as well go for the extra channels even if it wasn't the issue. I get a cable signal and can do a speedtest, but unfortunately can't actually browse the internet. It seems like Comcast was only able to partially register it, on the phone they indicated that it wasn't connected at all... Definitely looking like an external connection problem now. The signal seems to indicate better SnR but just like my ARRIS is only able to lock a single upstream channel. The download speed is also about 50% of what I see on the ARRIS- upload being the same.
I'm back on the ARRIS for now, based on everything maybe it is a miracle I have an internet connection at all right now. I have been in communication with ComcastAndrew who has been very helpful and it seems like having a tech over is all that is left to do.
... View more
I have observed that my upload speed is consistently around 0.9-1.0Mbps at all times vs the 6.0 that I believe it should be. I have seen however that my download speeds seem to vary with the time of day, 20Mbps or so during the day, 15Mbps in the evening, and in the very early AM up around 30Mbps. I haven't noticed my connection drop in about 2 days, I'm not sure if seeing the signal stats over a longer duration (unerrored/correctable/uncorrectable codewords) will be helpful, but here is an updated snapshot of my signal down the full length of my cable:
2-26-19_Residence Cable Modem Signal
Upon a fresh reboot, there are a few other error messages aside from the repeating "T3 time out" and "T4 time out" mentioning CM and TCS, here is a snapshot of that:
2-26-19_Residence Error Log
In an attempt to rule out the interior cabling, I connected the modem to a point about 3 feet into the basement, as close to the exterior connection as possible.
I can't use that point for day-to-day, I just temporarily cut the modem in there for debug purposes. The behavior is the same, only 1 locked channel and partial internet speeds with the same error messages.
This leads me to think that the issue must either be with the modem, or external from the house (house to pole, or more widespread Comcast issue). I'm no expert with reading the signal levels but it seems like the signal in my residence looks pretty good? Is there anything concerning at all about the most "direct" connection having such a low upstream power level? Anything that could help rule out or condemn the modem would be helpful!
... View more
I do need a splitter, a different one might be better. Without the splitter however, the experience is the exact same right now and speeds were around what they should be for over 2 years before yesterday. Straightening out some cable has reduced my upstream power from 52dB to 50dB. Swapping out a particularly ratty looking cable reduced it to 44dB. Here is an updated snapshot of the signals.
... View more
Interesting! I reviewed the post after I submitted it and they were visible for a while, must have been locked down later.
Current Reading (behind splitter)
Earlier reading (before splitter)
... View more
I have my own ARRIS SurfBoard SB6121 modem that I've used for almost 4 years without issue. The setup of everything in my current location is pretty much untouched, was working fine for over 2 years until the recent disconnects and larger issues I started seeing today. A few weeks ago I downgraded my Internet speeds from 120Mbps to 60Mbps. It may be a complete coincidence, but afterward I experienced one or two internet dropouts (that I was aware of) a week. Yesterday I lost internet 2-3 times, today I lost it and it was down for over an hour. There have been no service interruptions in my area and my neighbors indicate their internet has seemed to be fine (separate coax cabling). I'm hoping to get advice pointing to a possible connection issue or something else, not wanting to buy a replacement modem unless it seems like the likely cause. Prior today I was seeing about 70Mbps download and 6Mbps upload, very consistently. Now (if I have internet at all) I get around 20Mbps down and 0.9Mbps up.
The logs on the modem are flooded non-stop with T3 and T4 timeout errors;
-Received Response to Broadcast Maintenance Request, But no Unicast Maintenance opportunities received - T4 time out
-Started Unicast Maintenance Ranging - No Response received - T3 time-out
I've also seen some messages where 13 or so timeout messages were recieved and it forced a modem reboot.
On the status page most things are considered "Not started". In cases where these actually do get completed everything is successful down to "Register Connection", this fails. It says the "Cable Modem Status" is offline both when the other status' are done and not started, the difference being in the case where they are "Done" instead of "Not started" (with failed register connection) there is no working internet connection.
On the signal side of things, for the upstream I only seem to be getting 1 channel with successful ranging status. I believe the downstream SnR is fine, but could be higher and that the upstream power level is borderline too high. I live in a house split into 4 apartments so the cabling is a bit of a mess, but it looks like I have 2 coax extentions within the house and am also off a splitter. Setting up the modem before a splitter and extention does lower the upstream power level a tad but doesn't result in any speedtest changes or changes in modem status.
Here is a screencapture of current state, after the splitter and extensions:
Here is a screen capture of before the splitter and a single extension:
You can see the upstream and downstream channel IDs don't match, I have been seeing that a lot as well. The ranging status for the latter 3 channels is "Other" in this case and during a speedtest I was unable to get the upload portion to work at all. The downstream power level in this case is also positive instead of negative. The Downstream SnR is higher. Clearly if I could get a new direct connection, that would help the numbers- but that doesn't seem to be the issue since things still don't work setup that far down the line.
Any advice on things to try or investigate is appreciated!
... View more