[POCKET EDITION v1.19.31] "Unable to connect to world" when attempting to log into an external server

On MCPE 1.19.31 for both iPad and iPhone, I'm able to locate a server, see # of online players, and current ping. When I click "Join Server", I'm met with an error saying "Unable to connect to world" every time.

I tried the various workarounds I've found on the internet like creating/leaving singleplayer worlds, restarting the app and iPad/iPhone several times, and signing in/out of Microsoft account repeatedly. I even tried to use BedrockTogether to trick the game into connecting via LAN and encountered the same issue.

Featured Servers work just fine.