@Rakly3 I actually had "HEVC Video Extension Codec" installed, instead of "HEVC Video Extensions".
After installing the second one I was finally able to play h265 videos.
Although there are other problems. Videos freeze for several sec, then jump ahead for 5sec or 5min and often kill my link with pc. No idea what that's about yet, but at least the first problem of setting videos to 60Hz/90Hz h265 is resolved.