Gotcha!

From Plex’s site on the relay service:

Connections are limited to 2 Mbps maximum for streams (this applies to both Plex Pass and Remote Watch Pass subscribers)

Plex’s strengths is it’s ability to remotely stream without jeopardizing your network security.

Doesn’t the Plex proxy stream cap at 2 MB/s ?

So unless you are fine with such a low bitrate, opening a port with Plex is also required, be it done manually or with UPNP. (Disregarding VPNs here)

Or am I missing some other way to stream content with Plex?