Can't join my friends worlds, they can't join mine BUT can join eachother

I am unable to join my friends world(they're my kids so we are in the same house!).  We have occasionally had difficulty with this in the past when we were all playing on phones.  Now they each have switches and I play on my phone.  We have been able to play together, they on their switches and I on my phone but I haven't been able to join them since the new update.  They show up as friends playing minecraft and when I try to join it says connecting to world and then I get the screen, unable to connect to world.  I have also tried joining on another phone under my same account with no luck .  In the past I have tried signing us all out and back in to our accounts or having them leave and rejoin the world. I am sure there is an easy fix for this but I just don't know what it is.