I think nothing is connected there. Our setup SAT TV two devices, dish with double LNB. Internet via fiber optic, Telekom, their Smart Router. No problems. If there is no signal, then it is thunderstorm or heavy rain or something. Karsten
So, as I said, I would try turning off WLAN + DECT as a test. And then unplug the LAN cable again - maybe the TV wants to fetch some data about the program from the network and is failing or something..
A systematic troubleshooting can only look like this: all things not necessary for operation are unplugged. So only the TV with power and SAT cable, disconnect and/or turn off the rest. If it now works without errors, then reconnect one after the other.