I am not using VPN,my provider has built in VPN in its server!
Well that's wonderful and all but redundant... Your provider can have a vpn with the incorrect protocol and that protocol sometimes see harmful traffic and blocks it because iptv providers are constantly being attacked by who knows whom...
Wireguard blocks many stuff, that's why your channels get blocked for 5-10min sometimes and you switch to another channels in the same provider and it works without error... Meaning that live channel link will be blocked for a bit. Open VPN UDP is recommended on this cases, your case, because it uses 2 ports, so when it blocks the live channel link, the traffic will go through the other port, meaning you get small drop instead of network error or the freeze of dead...
Now random freezes are another story but that's not what you are complaining so...
If it was me i would tell your provider to put his vpn well you guess and buy a dedicated vpn myself so i can change protocol when i want, but that's just me...If you can contact your provider asking what vpn protocol he's using and if he can change it to open vpn that would be wonderful...