"Enable Relay" setting - seeking more info

Server Version#: Version 1.18.8.2527
Player Version#: Android 7.29.2.16071

Have Plex Media Server running on a Synology NAS. No issues accessing the server from devices on my LAN. When I’m away from the LAN, all I’m wanting to do is use my android phone to check if the Movie DVD I just found at the local flea market is one I already own. From what I’ve read in the Plex help, the limited data transfer rates offered by the relay feature would be more than enough for that purpose. I’m also anticipating that the relay feature would be more than enough to be able to get Sonos/Alexa devices on my network to access my music libray and start playback.

So, with all that said, what do you need to do to get the relay function working? Just check the “Enable Relay” function? Do you need to have Remote Access enabled, or should you have it disabled if you plan to just rely on the relay feature? Any other settings under either Remote Access or Network that should be enabled, disabled or have a value set?

Once all the settings for relay are configured and the Plex Media Server restarted, is there anything I need to do on the Plex app running on either my Android phone or my iPad in order to get the app to see my content?

I look forward to your response

Enabling remote access will enable direct if possible else it will enable relay.