Unable to connect to world

I am an android minecraft PE user and basically my friends nor I can join each others' world. I tried with friends having android and ios. They both have the most recent version. I have cellular data turned on. I tried signing in and out of my microsoft account, restarting my phone, closing all background apps and nothing happened. I even used another device's mobile hotspot to connect but all in vain. I even tried  However, there is a case where a friend is on nintendo switch and I'm able to join her world but she can't join mine. Could you help me please?