Unable to join a friend world cross platform (ps4)

Unable to  join my friend's world. I tried everything i could think of :

1. Restarting Minecraft
2. Joined random Minecraft servers
3. making sure that my IPad is up to date
4. restarting my Ipad
5. uninstalled Minecraft and reinstalled
6. Login off and log back in
7. asking my friend to make a copy of the world, and tried joining
8. restarting my wifi

none of my efforts above worked.