Problem with rpi 4 (with librelec) pluged on a 4k TV

hello! i'm having issues when a connect my rpi 4 (with librelec) on my 4k tv. The problem is, the tv does not recognizes (no image or sound) the device but when i connect the same device on a Full HD tv it works fine. Can someone help me please? I'm trying to fix this a while, i'm asking help here because I dont know what to do anymore.

Thanks!

Quote from Da Flex

Have you tried a different HDMI cable? 4K needs an HDMI 2.0 or 2.1 standard cable, because of higher data rate.

Thanks for answer. I tried some i had here, none worked, I can try on an HDMI 2.0. Just asking, there is anything I have to do on settings? Thanks again.