I’m using my Television, between other things, as a secondary display for my two PCs, a desktop and a laptop. Both of them runs Window 10.
The television is connected to the house wifi and communicate with my PCs through “Wireless display”.
The TV works well when used as a television, no problem in streaming Netflix or YouTube and it performs well when used as a secondary screen for my laptop PC.
When used as a secondary screen from my desktop PC, the image in the TV “flicker”: every second or so the image blurs for an instant before going back to normal. The issue remains no matter if the PC monitor is mirrored, extended or if only the secondary monitor (the TV) is active.
Laptop and Desktop PC seems to output at the same resolution (1920 x 1080) and refresh rate (60).
Lowering the refresh ratio output of the desktop PC from the default 60 seems to improve the situation (it makes the flickering less visible) but do not solve it.
The TV specifications claim that the maximum available resolution is 3840 x 2160 but this value is not listed as an option by windows. Raising the resolution from the default of 1920 x 1080 to 1920 x 1200 (the only higher value that seems to be available) crash the connection between the TV and the desktop PC. The only way I was able to reconnect TV and desktop PC after this crash was to Format my PC (advice from Toshiba support team).
Lowering the resolution do not seems to have an impact on the flickering.
The Graphic card on my desktop PC is NVIDIA GeForce GTX 970. My Windows and my Graphic card drivers are up to date.
I tried already to reset the TV to factory setting and I already formatted my PC.
I contacted already Toshiba support team, the local team was unable to solve this issue and I’m waiting to be contacted by the head office but I hope to solve the problem before that.

I bought a new 50" Toshiba Ultra HD TV model 50U6863DB ( Specifications: https://toshiba-tv.com/uk-uk/50u6863db# )