One other thing I want to mention, there seems to be some difference between the ASUS and Merl.in firmwares. When I use ASUS firmware - the please streaming won't work outside of my network - when using Merlin's firmware - the remote plex streaming works fine. As far as I know , I am using the same setting for both... any ideas. It is not a big deal because I prefer Merlin's firmware - just curious mostly.
I know there's at least one issue with the Plex that is resolved in my firmware because I run a more up-to-date version of miniupnpd (its author resolved the issue a few months ago). Could be related.