Hello, I've been having an issue lately, this recently popped up today ( 6/22/16 ) on Minecraft Realms. This issue also appears on multiplayer server's.
. The game freezes for a second
.Constant crashing
.Innability to use elytra's or fly in creative mode
.No other details
Linked issues
Comments

There's a bug in Minecraft 1.10.1 that crashes your game when connecting to servers.
See MC-103981 and MC-103978 for more info.
In the meantime, you can safely downgrade to 1.10 until a proper fix is released.
To change your game to a different version, start the launcher. Select Edit Profile.
In the "Use Version" dropdown menu, select the game version you want. Then click Save Profile.