Amazon Fire Stick Plex app shows error symbol for server

Plex Players Streaming Devices
2

You may need to disable secure communications on the server and in the Plex app on the FireStick. See thread linked below for details.

Any reason you’re still on 1.18.5.2260? That release will be 2 years old in January. Among other enhancements, updating to a current release will let you enable secure communications between the Plex Server and Android devices.