Upstream power high even at outside cable drop

I previously had service working in this location for 4 years with no problems.  I am now unable to keep a cablemodem connection, and it often goes out for days at a time, with no number of reboots helping.  I have had techs out twice, two weeks ago one ran a new line from the drop to the pole and said the signal wasnt great and probably needed work upstream from me and would put in a request for technicians to check.  The second said everything was fine, and maybe it even was when he was there, but the internet stopped working within the hour when he left.  It does sometimes work for a little while every couple of days.   Neither the technician nor tech support has been able to tell me if there is any work scheduled.

I went and got a new XB8 cablemodem from xfinity.  The old modem was not working when I unplugged it and when I plugged in the new modem, it worked for about 8 hours, but then stopped and hasnt reconnected now in 24 hours with multiple reboots.  Cables have been changed to those provided by xfinity.  There are no splitters.

I have taken the modem outside and plugged it into the drop from the pole outside my house.  It can sometimes connect there a little better, but the connection still drops out repeatedly and even when its connected the latency is all over the place, with pings to 8.8.8.8 being 15ms or 300ms and wildly variable speedtests.

The screenshot below was taken at the drop outdoors, showing a 52db and 58db upstream.  Often this is worse with 55db or 59db and will not connect at all even outside.

How can I proceed?  Tech support says I will be charged if they come out, but this doesn't seem like a problem internal to my home if it wont work at the demarc and I cant guarantee itll be not working when they arrive.