Echo Dots on bridged internet connection don't find my server

My house is rigged with several Echo Dots, some of which are connected to the internet via a router that is connected to my primary router/modem over a wireless bridge. Those particular Echos fail to find my local Plex server, but still find Plex servers that have been shared with me. I’ve confirmed that my Plex server has remote access.

I’m fairly certain it’s not an issue with the generation of Echo I’m using. Older ones that are directly connected to the primary router play music off of my local server just fine (as do the newer generation Echos). The only thing I can identify is the bridged internet connection.

Any suggestions?

In case anyone else encounteres this, I solved the problem by disabling and re-enabling the Plex skill in the Alexa app.