Eh, my ISP (Comcast) has extremely unreliable internet across two different homes I've lived in, to the point that I absolutely rely on having both a 5G modem and a wired one. If my 5G signal was strong enough to keep me going on a rainy day, I would absolutely ditch the wired connection and its flaky mysterious dropped packets.
Don't get me wrong, I'd much rather have a wired connection. But if my isp can't even be bothered to give me a functional connection more than 90% of the time...
I spent 20 hours diagnosing my internet in a situation that sounded like yours. The solution actually showed itself: the copper from the street pigtail had a connection end that was improperly installed. It grounded into the protective braided metal around it, and each time the isp came to diagnose, they disconnected the bad wire then measured from the street and said "no issues". I felt really triumphant when that was corrected.
Don't get me wrong, I'd much rather have a wired connection. But if my isp can't even be bothered to give me a functional connection more than 90% of the time...