So I've figured out what happens..
Roku 10.5 stops broadcasting the Bonjour mDNS service after about 15 minutes. Roku TVOS 10.5 has mDNS issues that have been overlooked by Roku.
Grab a the "Flame" or "Discovery" app on the App Store. It allows you to browse the Bonjour services on your network. Upon booting and until about 15 minutes after the TCL Roku TVs both show up in the services list. They drop from the list after about 15 minutes, when the TVs stop broadcasting the mDNS info.