I just wanna share my experience. I'm using a CCWGTV, so I'm limited when it comes to using ethernet, unless I purchase a usb c hub. Connecting my dongle to 5Ghz wifi shows 250mb/s when performing a speed test. It's good enough for streaming Youtube and movies on services like Stremio and CinemaHD, but it struggles with IPTV! I'm using Tivimate and it buffers like crazy. I thought the problem was with my provider, until I came across a post that suggested switching to 2.4Ghz. As soon as I did that, bam! all that buffering has gone away, and the IPTV works flawlessly. I don't understand why because 2.4Ghz is giving me half the speed of 5Ghz! It seems like 2.4Ghz is more stable when it comes to IPTV streaming.
It depends on your setup. 5Ghz will provide more bandwidth (and faster speeds) but the distance and wall penetration of that signal is much reduced. 2.4Ghz will go a lot farther and through walls better, so if that's the situation, 2.4 is the better option.