How do you play together in minecraft?

My girlfriend is playing on her mobile and I'm on the laptop. We both have Mojang. In the past, we could easily play together. We have friends and also play in servers. I can sometimes aucj into their world. Only sometimes not. She can never go into mine because that invites her to go in and then she gets kicked out. How can we play without a realm together in a world that goes into mine?

Are you both in the same network? What does the Windows Firewall look like? Are both versions original?