Remote Access

I have never been able to get Remote Access working and I have come to the conclusion that my ISP uses Carrier Grade NAT which makes it impossible to foward ports.
I was away from my house today, sitting in a waiting room and thought I would try the Plex App and found I was able to watch a movie i have stored on my NAS (WD My Cloud Home)
If Remote Access isn’t enabled, why was I able to view my content ??

Accessing via Plex Relay, which tunnels the stream through a server at Plex. The stream is limited to 2 Mbps (1 Mbps w/o a Plex Pass).

You can monitor playback via Plex Dashboard → Now Playing. Plex Relay connections show up as Indirect, instead of Remote or Local.