New Hub 5 keeps dropping internet connection
I had a new Hub 5 a few weeks ago (replaced a Hub 3 and briefly a Hub 4) and have now had a few times where the internet just stops for a few minutes, then comes back.
During the outages I am able to talk to the Hub 5 quite happily via Wi-Fi and see its status page , so this seems to be some kind of internet/cable modem issue rather than a Wi-Fi problem. All our devices lose internet at the same time, even those cabled into the hub via Ethernet.
Note that we had zero problems like this with the Hub 3 for all the time it was here (a week or so prior to the Hub 5 arriving).
I had a look in the Hub 5 status pages and during the outages had the following things logged:
| 24-11-2025 14:22:03 | critical | Unicast Maintenance Ranging attempted - No response - Retries exhausted;CM-MAC=70:7d:a1:74:e7:45;CMTS-MAC=00:01:5c:7b:ac:54;CM-QOS=1.1;CM-VER=3.1; |
| 24-11-2025 14:22:03 | critical | 16 consecutive T3 timeouts while trying to range on upstream channel 8;CM-MAC=70:7d:a1:74:e7:45;CMTS-MAC=00:01:5c:7b:ac:54;CM-QOS=1.1;CM-VER=3.1; |
| 24-11-2025 14:19:04 | critical | Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=70:7d:a1:74:e7:45;CMTS-MAC=00:01:5c:7b:ac:54;CM-QOS=1.1;CM-VER=3.1; |
| 21-11-2025 20:22:41 | critical | No Ranging Response received - T3 time-out;CM-MAC=70:7d:a1:74:e7:45;CMTS-MAC=00:01:5c:7b:ac:54;CM-QOS=1.1;CM-VER=3.1; |
| 21-11-2025 20:22:40 | critical | Unicast Maintenance Ranging attempted - No response - Retries exhausted;CM-MAC=70:7d:a1:74:e7:45;CMTS-MAC=00:01:5c:7b:ac:54;CM-QOS=1.1;CM-VER=3.1; |
| 21-11-2025 20:22:40 | critical | 16 consecutive T3 timeouts while trying to range on upstream channel 8;CM-MAC=70:7d:a1:74:e7:45;CMTS-MAC=00:01:5c:7b:ac:54;CM-QOS=1.1;CM-VER=3.1; |
| 21-11-2025 20:22:34 | critical | Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=70:7d:a1:74:e7:45;CMTS-MAC=00:01:5c:7b:ac:54;CM-QOS=1.1;CM-VER=3.1; |
| 16-11-2025 11:09:30 | critical | Unicast Maintenance Ranging attempted - No response - Retries exhausted;CM-MAC=70:7d:a1:74:e7:45;CMTS-MAC=00:01:5c:7b:ac:54;CM-QOS=1.1;CM-VER=3.1; |
| 16-11-2025 11:09:30 | critical | 16 consecutive T3 timeouts while trying to range on upstream channel 8;CM-MAC=70:7d:a1:74:e7:45;CMTS-MAC=00:01:5c:7b:ac:54;CM-QOS=1.1;CM-VER=3.1; |
| 16-11-2025 11:09:24 | critical | Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=70:7d:a1:74:e7:45;CMTS-MAC=00:01:5c:7b:ac:54;CM-QOS=1.1;CM-VER=3.1; |
| 14-11-2025 17:20:25 | critical | Unicast Maintenance Ranging attempted - No response - Retries exhausted;CM-MAC=70:7d:a1:74:e7:45;CMTS-MAC=00:01:5c:7b:ac:54;CM-QOS=1.1;CM-VER=3.1; |
| 14-11-2025 17:20:25 | critical | 16 consecutive T3 timeouts while trying to range on upstream channel 8;CM-MAC=70:7d:a1:74:e7:45;CMTS-MAC=00:01:5c:7b:ac:54;CM-QOS=1.1;CM-VER=3.1; |
| 14-11-2025 17:20:19 | critical | Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=70:7d:a1:74:e7:45;CMTS-MAC=00:01:5c:7b:ac:54;CM-QOS=1.1;CM-VER=3.1; |
None of that means anything to me, but I have found other people with similar issues and this being a total pain to get sorted. I've just called the VM support number and they're going to book a techy to visit on the afternoon of 26th, but being an intermitted fault I suspect it's unlikely it'll do it whilst they're here. The person on the phone saw no issues when they looked at the connection (I'm guessing they don't get to see the Hub logs...)
In the 3.0 Downstream Channels bit, one line stands out as significantly different to all the rest:
| Channel | Locked Status | RxMER (dB) | Pre RS Errors | Post RS Errors |
|---|---|---|---|---|
| 8 | Locked | 39 | 196 | 761 |
All the other channels are at low single digits for Pre RS Errors and zero for Post RS Errors. No idea if that's related? The log messages are talking about upstream channel 8 and the above is downstream channel 8.
Also, when we had the Hub 3 fitted years ago, a 6dB attenuator was fitted. I have no idea if that's still needed, I recall the installer saying the signal was a bit strong. Perhaps the Hub 5 would work better with this removed, or maybe it even needs a higher value attenuator? Can anyone tell me what range of numbers I should be looking for in the Downstream or Upstream sections? I'm guessing there's a normal operating range for the dBmV power levels?
Thanks for any help, advice and suggestions đ