Aloha all! Same problem as everyone else reported here since updating to 12.1. Devices involved: all iOS (iPhone and iPad). Interestingly, after updating to iOS 9 last night with a resulting complete "reset" of all the devices, we were able to connect via LAN again. However, this only lasted for a short time. During that time we experimented by logging in and out at intervals with success. After a period of about 30 minutes, we tried to join by LAN again but were unable to see each other's worlds-just as before. I hope this report lends some clues to an eventual fix. 🙂
Aloha all, again! Update. Following the recommendations, we were able to connect via LAN. The fix lasts temporarily and needs to be repeated each time a new game session is started. If you log out of the host server, you will more than likely not be able to log back in without performing the "fix" procedure. The procedure that worked for us is as follows:
1. Quit Minecraft completely (force quit). Press home button twice. Sweep left or right to find Minecraft PE. Swipe up to quit the app from running in background.
2. Place iOS device in Airplane mode and wait a few minutes.
3. Reset/restart your wifi router (turn on/off or unplug/plug in). Wait a few minutes between off and on in this step as well.
4. Restart wifi router, turn off Airplane mode on devices, start MCPE on server/host device. Guest devices should see the host on their lists now (at least we did). Log in and have fun! (Again!)
Keep in mind that if the guest logs off or the server quits, the above procedure needs to occur all over again. It was nice to be able to play together again 🙂. Hope this helps some out there...