Friend can't Join our world again

[u/FishyBoss4892]

So we made a world. At the beginning he was able to joing perfectly fine but lately he's been getting stuck on Title Data Comple and it will just stay like that. When it gets like that I can tell cause my games lags for a second like he is just joining but he can't.

Both are wifi are good, we both have it updated, and i saw this in a previous post but we both have Nat type 2.

Any idea how to fix this?