Channel number limit

Plex has a limit of 420 channels on a tuner, above which it starts to behave badly. If you start telly with a channel list that exceeds 420 channels, telly will quit rather than take the chance of bad behavior.

Of course, most IPTV accounts come with far more than 420 channels, which means you need to prune your channel list somehow.

There are a variety of ways to do this, some free, some paid.