Update issue

Hello, my son's friends are playing on their switches and pcs and have updated to version 1.17 and he can no longer connect with them, it says "outdated client" to us when we try to connect. I have looked to see if there is an update on the App Store but it says I'm up to date. Is my son not able to play with them anymore now?

many thanks 

 

Siobhán o'neill