So yesterday I tried to install PlexConnect into my ATV3 and long story short, it did not work because according to Terminal, Port 80 was already in use. So the real problem is that after that I haven't been able to see the Mac Plex Server in my Roku 3 or my Galaxy 3. Also, tried to use Itunes home sharing and was not succesful. I turned all the Sharing options "On" in Settings. Am I missing something? What can I do to fis this issue?
-> PlexConnect is never installed "in" an aTV. It is just an application running in parallel to the server.
-> Depending on how you shut down/killed PlexConnect, there might be some processes left. I don't see, how they would interfere with the rest, but you never know...
Did you change any DNS settings, in aTV, your router, Roku box?