I’d be slightly astonished if the tech did actually leave any notes, I suspect his or her prime concern is to simply get onto the next job. I think you have a cable connectivity issue, the upstream power is gradually ramping up to compensate and eventually can’t go any higher at which point it triggers a reset of the hub - rinse and repeat. This isn’t something that you will see in the logs and the hub stats are simply a snapshot of the situation at that time, so you won’t necessarily see much obvious there either.
The suggestion that you get a Hub5 was actually a load of rubbish, it won’t help in any way, shape or form - but, like I said, they really just wanted to get away and on to the next job.
You’ll need another tech visit, I’m afraid.