Everything is fine so far. PMS discovery is done as soon as an aTV hits the trailers app.
Very early in the project it was done right away... but when multi aTV/multi user functionality was added, it got kind of postponed.
So could it be something I need to update on the aTV? DNS is setup correctly. Possible the trailers cert files? I do recall having to do something with them before. I do see the DNS request received messages when accessing trailers. But never shows up finding PMS.
Your log should show DNS requests, usually "forwarding" or "intercepting" with trailers.
And yes, your aTV needs a certificate to trust your PlexConnect host.
Got it working, I had to add in the certificate on the aTV.
Also had to disable my VPN. It was causing issues for initial connection.