Since the release of Minecraft 1.16.100 for the Bedrock community players have been experiencing a whole range of issues, the developers are aware of the current issues and have already released a patch which is version 1.16.101
NOTE: This hotfix is only available for mobile devices. Multiplayer is still fully compatible with other devices running version 1.16.100. Please report any bugs you find on bugs.mojang.com and post feedback to feedback.minecraft.net.
- Fixed players unable to connect to Realms when playing on cellular data on mobile devices (MCPE-55405)