A monopoly ISP refuses to fix upstream infrastructure

I had a similar problem with a DSL line ages ago and what finally fixed it was to upgrade to business-class service, complain to business support, and they sent a tech who eventually found what it was (a tester on the line painted over so as to nearly be invisible). After it was fixed I was able to downgrade back to consumer DSL.

everybody has a fraction of that speed

I found that logging into the cable modem itself and getting the signal levels and modem event logs helps. The poster seems to just be logging IP reachability. You have to keep repeating that modem logs show the problem is outside of my house until they send a technician. Then you hope the tech knows what he is doing enough to verify the issue and call the right person.

It took about 2 months and 5 visits to get my outages fixed. I also had to get some of my neighbors to report the outages.

I had a similar problem with a different ISP, Optimum, in Northern NJ. It wasn't as regular as the author's problem -- my cable modem would desync intermittently throughout the day despite the signal strength numbers being in spec.

I replaced everything downstream of the drop from the street, all new wiring inside, a new modem/router/etc. All signs pointed to the problem being outside the house. I went so far as to connect an oscilloscope to the coax line to look for patterns. I discovered that if I physically manipulated a particular section of the line from the pole, a huge interference pattern appeared and the modem's connection dropped. Eventually I could reproduce the connection loss fairly easily.

Convincing the ISP to actually do anything about it was much harder. Despite first-hand evidence that the coax from the pole needed to be replaced, their tech support insisted that someone had to come into the house to inspect the interior wiring. No amount of insistence on my part would convince them that it was not necessary. The building was a vacation home, and this was during peak COVID time, so there was basically no chance of that happening. The appointment came with threats of service charges if they sent a tech and could not enter the building or reproduce the problem, so I cancelled it.

Coincidentally, I happened to discover that the mayor of the town had started a hotline specifically for reporting home Internet problems in the town. So I sent in a message to that service, not really expecting anything to come of it. But shortly after I get a phone call from some higher-up department of the ISP. They had a truck out within a few days to replace the drop -- with no one home -- and the connection was rock solid ever since.

This experience taught me that ISPs often have distinct support channels that governmental departments use to contact them. I think they called it the "executive support team" or something along those lines. Basically, if you can get a message in that way, it's possible to circumvent the useless consumer-level support. Long story short, I think escalating this through the local or state level government may be the author's best shot at getting this resolved.

Its not like it is some monumental task. Fiber is cheaper than copper, and we managed to lay copper telephone lines and power lines to everybody. Where I live right now didn't even have DSL available at any point in time, the local telecomm didn't want to spend money on replacing some of the poorly functioning 60 year old copper lines despite everyone clamoring for any kind of wired connection. And yet a startup ISP managed to not only lay down gigabit direct to home fiber to the entire county in under 2 years, but they provide it for significantly cheaper than people's wireless/mobile internet. And they are still expanding across the entire state so are obviously earning money from it.

Existing telecomms have zero excuses after being given billions of dollars to do this after seeing startup fiber companies manage to do it profitably after the fact in even in some of the lowest density areas east of the Mississippi.