Thanks drewbie
Good news is that I relaunched via Terminal and now all apps, including Trailer/PlexConnect, is running successfully on my ATV. I am more of a 1.0 rather than 0.1 consumer of tech stuff, so Terminal commands are rather beyond my comfort zone and I can say for certain that I don't keep Terminal app open as a matter of course in my daily computer usage :unsure:
Thanks again to the PlexConnect community, both for the creativity and the support.
If I may offer one suggestion ... update the installation instructions (say per https://github.com/iBaa/PlexConnect/wiki/OSX-and-ATV-with-5.2-firmware-and-ethernet-internet-connection-installation-guide) to state that the Terminal stuff needs to be repeated each time the related device is restarted and Terminal window kept open. Perhaps this may be obvious to some folks but it was not to me.
Cheers ... riding off into sunset ...