Some providers rotate URLs or require VPN. Always test the M3U URL in VLC or browser first.
Once configured, TiviMate remains the best interface for IPTV viewing. Take the time to organize your "Favorites" list, and you will have a TV experience that rivals traditional cable. tivimate iptv player m3u playlist url work
Edit the end of your M3U URL from &output=ts to &output=hls and reload the playlist. Some providers rotate URLs or require VPN