colaIsolate the scope
Try another live channel and an on-demand title. If only one source fails, record its name and time for support. If everything fails, check your account status and whether another stream is already using the connection limit.
Check the local connection
Confirm another internet app works on the same device. If possible, compare Ethernet with Wi-Fi or move nearer the router. Pause large downloads for a controlled comparison. One high speed-test number does not prove a stable route to a streaming source.
Compare source and player settings
Try an available HD version instead of 4K, then reopen the player. If the player offers supported decoder settings, change one setting and retest. Keep a note of the original value so you can revert.
Ask for a targeted check
Send the device, player, channel, time, connection type and the tests already tried. Support can check an available server alternative. A VPN may change routing, but it is not a guaranteed fix and can also reduce performance.