On ios there is an app called multiplayer terraria, it is a seperate app. It uses host finding vpns to make terraria able to be played online with anybody who has the app. Mainly people join and fight bosses or ask for things (noobs)
I have myself and all ive seen is people with high end stuff kill others while weaker people have their own servers asking for things.
Sigh~ if only the devs would impliment this themselves