Hi
@Funtime_goal if you’re having problems while using Zerotier you’ll need to ask Zerotier. The Terraria developers did not create Zerotier and so cannot help fix whatever problems you’re having.
If you’d like to play multiplayer without using a third-party app (like Zerotier) you can check out this article that goes into a lot of detail:
Mobile - Terraria Mobile 1.3 Multiplayer Setup Guide
Just a quick tip - playing with third-party apps can create unforeseen circumstances (I’ve seen other players start to have problems loading their world), so unfortunately whatever issues you may come across are not going to be something that can be looked at.