Plex support is exclusively through the forums. Plex employees, team members, and forum moderators (ninjas) do monitor the forums and respond. Obviously there are a lot of issues posted, so they do their best. There are also many knowledgeable (more so than me thankfully) users that will try to help as well.
The log file that is most typically beneficial to start with is “Plex Media Server.log”. If you want to investigate yourself then here is a thread was very useful to me to know what to look for.
While people do post the logs, there is information specific to your setup. For example, IPs of devices on your internal network, OS version you are running, timezone you are in, etc. However, there are no tokens that would let someone log into your server.
I never discount anyone’s security concerns. If you aren’t comfortable posting your logs then there is absolutely nothing wrong with that. You can wait for one of the Plex team to respond and DM (direct message) the logs directly to that person.
Welcome to the forum!
