Not sure if you want to put your games direct ip on here. Don't want you to get unwanted guest poping up on your multiplayer game.
Couple troubleshoot questions:
Are you both playing on the same Internet or separate? Direct multiplayer with the same Internet, the player's server will just show up as one of the connect options. If not you have to use the ip option.
Are You both using iOS device or mixed, steam?
How long is the host side running before the other connects? I notice the host should run for a few seconds before the other connects with the ip.
Check to see if your Multiplayer restrictions is not on in the ios setting?
Another culprit could be Slow Internet connectivity. Is both of your internets pretty good speed?
Here is a guide for steam/ios connectivity.
viewtopic.php?f=41&t=30772&p=385069&hilit=Direct+multiplayer#p385069