@DjShadow I had a similar run of really high uncorrectable errors, probably more so than yours but it also lead to my connection speeds dropping from 1000/100 to ~5/10 at its worst and a reboot of the technicolor box would resolve it and then it would be back to the same in a weeks time. After a few calls back and forth with Vodafone, a technician was sent out to have a look. There were no issues identified with the signal from my end and the ISP end but what he did do was to replace all the connectors on my line from the street all the way to the technicolor modem. This appeared to resolve the issue to the point where I do not get the speed drops or high errors. At the moment, I am seeing 3867 errors on the downstream channel 1 and this is after 9 days of uptime but no speed issues. I have only had to reboot the modem once since this was done but even with a few months uptime, the errors were minimal and only one one channel.
My parents connection ended up having the same issue and to my surprise, the last time I was at their place last week, I rebooted their modem (weekly routine) and I got a call from the vodafone tech team in about 30 mins of the reboot to advise that they saw the connection drop and that they were seeing some issues and booked a tech to come out and do exactly what was done at my place. This was done this monday afternoon so I will pop in over this weekend to check out the stats and speed to see if it has resolved their issues as well.
When i receive fault tickets similar to this. I will replace every connector in the line and also swap out the isolator in the grey box on the side off the house. The most common fault for uncorrectables is a loose F-connector......somewhere. They can come loose over time and a very common cause of faults, not only on FX modems but also on Docsis 3 modems also. Its just that the FX modems work on way more channels and are vulnerable to even the slight issue for a connector. Last week I went to a customers house for the same issue and spent over 1 1/2 hours there. The fault ended up coming from a 2 way splitter up in the ceiling hidden underneath batts which had corrosion on one of the ports, it was used to feed an old tv connection years ago. Removed the splitter and replaced all connectors from the pole to the modem outlet and 'guess what'. Fault cleared up straight away that i was seeing on my meter and customer now has a consistant 930/100 speed. It bugs me but 4 other techs had been there before me and had not bothered to do proper trouble shooting. At least the customer is happy. Now wainting for the next one to come in :)