Modem: uncorrectables, T3/T4 errors

Hello Everyone,

We had an ARRIS SB6183 modem. Two years back we started getting random disconnects on our modem (coincidentally around the time they put in a new gas pipe in the street, which might be unconnected).

Over the years this progressed worse until the extend we had daily disconnects (most of them during the night or early morning).

Sometimes it went back with a soft reboot, at other times we had to factory reset our modem and after reconnecting the connection was stable till the next disconnect. I also started taking notice of the modem event log. I am currently going for a bachelor degree in cybersecurity and networking, so I am learning fast. I noticed there are a lot of T3 and T4 errors and sometimes even T5 and T6.

We went through every hoop of retightening every connection. We also removed all splitters. There was on near the cable outlet in the wall near the modem, and one in the comcast box.

There used to be an 6 or 8way splitter (previous homeowner wanted cable tv in every room in there before a technician actually took it and replaced it with a 2 splitter. We are pretty sure that was not his splitter and he just took it for it's value, but that was a few years back before we had knowledge what is really was)

So currently there are no splitters what so ever. The incoming line in the comcast line, goes directly into the cable connected to box to the cable outlet where the modem connects to. The coaxel cable from the modem to the wall outlet has been replaced (several times and now has a brand new one). We still have some splitters (not golden as I read before that's important) if needed. We even got a new one (silver from commscope) with the new comcast streaming device we have not yet set-up.

Against better judgement, as it's know helpdesk blames faulty modems first, we replaced our modem with an ARRIS SB8200. Our old modem was 4-5 years old, so that's pretty aged, but I rather had waited until DOCSIS 4.0 is out, but I digress.

Yesterday we activated the new modem. So far no disconnect noticed (maybe it did, and it fixed itself when we were asleep). But dispite that there are reasons for concern. Even after one day there were correctables/uncorrectables. Even the eventlog is filled up. After the last event 7/29 16:29pm I factory reset the new modems to bring the correctables/incorrectables down to 0 and see what it would do in a day. They are filled up again (see screenshots below). I am concerned even despite no noticable disconnect yet, it's only a matter of time.

Before on my old modem, and new modem all the SNR and Power levels were all inside the ARRIS recommended parameters

Yet today I noticed the last upstream channel is 52.0 dBmV, 1dBmV above the recommended. This is new.

My question is: anyone have an inkling what might be going on? My first and still current thought is that there is a problem with the comcast line that runs from the ped to the box on the side of the house (noise?).
Any suggestions what I should do? I heard about attentuators if the dBmV is too high, but honestly I am unfamiliar with them and it's only one upstream channel. I don't want it negatively impacting downstream or other channels (if that's a possibility). Would a splitter, that we have plentiful now, do the same trick?
Yesterday, before I noticed the surplus in dBmV, I was even considering getting  a splitter with an active return.  Luckily it was unavailable. I now think it would have done nothing.

I want to exhaust every avenue before calling in a tech. Currently it's probably a pain to get a tech over due to the pandemic and we want to avoid possible charges. So any advise is welcome.

7-29 549pm - 1 (status)
7-29 549pm - 2 (event log)
7-30 133pm (status)
no new events logged.

Note: I have found other topics with similar problems. I believe most confirmed my susicion, but a lot of topics don't get updated by the OP when the problem is solved. I promise I will update this.
Note 2: I am aware the 159 channel might be a wrong read due to a firmware issue.