@zooropean 

A different user with Deco M5s had the same issue: https://forums.plex.tv/t/plex-on-a-mesh-network-only-achieving-indirect-connection/356659

The problem was their computer's firewall the plex server was on.

@Tony 

Hello there,

I saw that post over on the Plex forums awhile ago and I am pretty sure I checked the Windows firewall.

But I can check it again and report back.

I doublechecked the Windows firewall and all of the Plex services are checked to allow through the firewall.

@zooropean 

Other people eluded to adding /plex.direct/, but with the Deco unit I do not think that option is there, only to change the IP of the DNS servers. There was another mention of disabling the security feature that prevents DNS relay attacks.

If you happen to have another router, use that router as the main router, and connect the Deco to that, and set the Deco to AP Mode. The Deco will still operate as a mesh network, but not have any of the routing features: https://www.tp-link.com/us/support/faq/2399/

@Tony 

Sounds like what I had read about a DNS rebinding issue as a potential cause.

I do still have my other router.  This issue was not present when I used that router.

I can try the connecting the older router but I hope in the future the Deco can get updated with more functionality regarding DNS management.