check box display settings.

cable usually not a problem.

2 considerations:

1. what do u usually watch with the box-TV?
if mostly 2160p hevc playback, set to 2160p 24hz as this is most common.

if mostly 1080p playback and other apps... best to set to 1080p 50hz... becos most live streams are in 25hz, some 30hz.
if yr firmware is up to date (2.1.4), it does auto frame switching; so this part is actually taken care of.
only that it is annoying to see the messages flashing on the tv every time there is a hz change when u change a video stream.

2. how good is yr TV upscaling?
if v good, u might want to set to 1080p for 1080p/lower streams, let TV upscale.
the box can be set to 2160p to upscale too but it may come out not as good on yr tv - this u gotta try and see.

any one try Dolby Vision file with this player? will it still able to play or black screen? some of the 4k bluray movie files already come with Dolby Vision....