I have two V6 boxes on the same home network. Let's call them V6-1 and V6-2.
V6-1 often, but not always, exhibits :-
These problems occur whether the box is connected by cable or WiFi. Items 2 & 3 are corrected by restarting the V6-1 box. Online checks and on-board diagnostics show no fault.
V6-2 is connected via Wi-Fi and behaves impeccably, showing none of the above issues.
have you tried a different HDMI cable, or different ports?
Also have you tried swapping the boxes around, then you you should be able to determine if it's a box issue or technical