Update.
Hit a few roadblocks along the way… but it’s up and working.
Had to remove the Plex the media server preferences and the .pid file so that I could find the server again on my home network after moving it to the TPLink router.
Then I couldn’t “claim the server”, so searched around and found @ChuckPa advising another user about a similar issue at Can't claim Server
Now it looks to be all working, fully accessible outside the network.
Thanks guys.
