Hi @Roni737 ,
I'm assuming the TV is connected wirelessly ?, is it a significant distance from the router ?
There are a few things you could try to see if it is Wi-Fi interference causing the problems.
Split the SSID's on the router, this will allow you to give the 2.4GHz and 5GHz networks different names, so your Wi-Fi devices will then see those two networks separately, you can then try connecting to one or the other to see if one gives a more reliable connection than the other.
Change the channels that your router broadcasts the Wi-Fi signal on, you can use free smartphone Apps like this to see what channels are being used within range of your smartphone, you can then change your router to use channels that are less congested.