LAN multiplayer games are not working properly

(Please understand that I am using machine translation as my English is not very good!)

When my mobile data was unavailable, I turned on the hotspot to connect with a friend.When I enter the world, the multiplayer online option is automatically disabled

 

Reproduction Steps
1. Turn off the 4G network.
2: Turn on the hotspot and let a friend connect
3, open Minecraft.
4, enter a world and find that multiplayer is turned off