Every live stream I've used on my Android TV Box is experiencing buffering at some point. Can anyone offer any help or advice to a noob or somewhere to get better more reliable playlists (I'm only interested in live sport)?

I have an Android 9.0 TV Box 4GB RAM / 64GB ROM. It is using a wired ethernet connection. I get 105mbps+ download speed on my devices (I am from UK and with VirginMedia). I have ExpressVPN installed on my Android box; And when connected to VPN, I switch country, which I auto connect to when Android Box turns on, and I get 45/50mbps+ download speed and ping of <25ms. If I switch to UK servers, then I still get similar speeds, maybe a bit faster, but <15/20ms ping. Upload is 9mbps if that matters but I am not uploading anything.

Also I am the only one connecting to the router. It'll just be the android box (wired), the tv (wired), and my mobile (wifi) connected to the router and the TV and Phone won't be doing anything strenuous (TV's being used by Android Box!)

The IPTV's I am using are two free ones (I can name them if it's OK to do so - I'm not selling anything, both are free). The one IPTV uses a different player on device - either uses Perfect Player or the built in video player, both buffer. The 2nd IPTV has it's own player; again buffers.

This was also my last experience with another IPTV as well a while ago; that time around I paid for a 24/48 hour pass and it just buffered constantly - so I'm wary of anyone selling me anything - not that anyone can do anyway as per the rules

Football/soccer is back very soon and I can't go the ground, so I was giving this Android Box a go, but it's just frustrating to watch. Please help