Technology problems

There's a couple different ideas that come to mind. Some of them good some bad so keep that in mind.

First: Turn off your wifi. Tell everyone to download whatever they need so they don't need the internet. Most spell apps are offline available. And they don't need to check for rules by googling. The Dm gets to make the call more or less.

This is an extreme option. I wouldn't start with that.

Second: I would straight up talk to the players. I'm not a fan of just blanket discussions. Talk to the troublemakers. Let them know that you worked hard and you want their full attention. Set up plans for phone time. i.e. If you're expecting a call have your phone ready. Phone on silent. Try and use your phone as little as possible.

Last: Try and make the phones part of it. Send secret messages to the player on their phone. Tell them that only they see it as something else is occurring. Player 1 is on their phone while player 2 is rolling an investigation. Send a message to Player 1 saying they see...
Once the players start to notice what you're doing it will almost become concerning when their phone goes off. You can then use that to your advantage and send random messages that have nothing but "Hi"