Can't connect to remote server with Fire TV on Echo Show 21

I have an Echo Show 21 with a built-in Fire TV. I set up the Channels app and have two Channels servers: a local one at my house and a remote server at another location. When I try to connect to the remote server, it takes me to the authentication page to authorize. I authorize, but it still defaults back to the local server. I can easily swap servers on my iPhone with no problem, but the Fire TV is the device giving me this issue.