Sorry, I’m not accepting that.
Are you using a current version of the Plex server? Without using a very old version, Plex is unable to tune channels.
EPG issues since the new update to Plex server. Channel Matching not matching the guide - Live TV & DVR - Plex Forum
How do you select your channels in setup?
Which Ceton do you have?
What OS are you running the Plex server on?