Hello,
Thank you for answer and sorry for slow response. I have a very unstable internet today so I can get some data from it. My laptop is pretty close to router.
first image: speedtest test ping 48 instead of 5-10(at least 5 times longer), speed is 21.20 instead of 250mb(10 times slower)

"Could you post one or more pictures of the AOP (main outlet in meter cupboard or living room) and cables, plus splitter(s) and signal amplifier, as applicable?"
Do you think does is matter? It was much better 2-3 weeks ago, I didn't change anything
Also I attached Downstream, Upstream and Network Log
and PingPlotter screenshot

just as an addition: I have a lot of video meetings during the day and have disconnect almost in every meeting.