@David-TP It's TCL S5200. Sadly guest network didn't help. The dropping frequency is like between 15 minutes and 24 hours. Static IP don't work either. All the settings on the TV is on so it should keep the network connection active in standby and (for example) wake the TV up by casting something.

Hi @David-TP! I have now connected one of the TV's to the nearest satellite unit via ethernet and i'm waiting to see if there is any difference. The problem if that works is that the rest of the TV's are to far away to use Ethernet so they must be connected with Wi-Fi. One of the TV's is connected to the main deco and the other three are connected to a satellite deco. And it doesn't matter if the mesh function is on or off, they disconnect anyway. I've already tried to turn of beamforming and fast roaming and that didn't work. I'm thinking that if the TV's (which only connects to 2,4 ghz) is trying to connect to 5 ghz in standby and therefore losing the connection? But I got lots of IoT units that only works with 2,4 that never loses the connection.

  @David-TP 

The new TV I tested held the connection in standby mode if it was connected through Ethernet. However, I got my old TV's back (TCL ES565) since I would rather have the 1600 $ back in this european economy right now. And my old TV won't hold the connection in standby even with Ethernet. I've read about some devices that have issues with Wi-Fi 6, so that might be it. Or the network card of this modell from TCL sucks...