I just updated to 1.16.40 and I can connect to realms just fine with only mobile data connection. Now that I am updated to 1.16.100 this error screen shows up forcing me to connect to wifi when I don't have one. I certainly cannot afford to have a wifi atm.
Thank you for your report!
We're tracking this issue in MCPE-55405, so this ticket is being resolved and linked as a duplicate.
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