IOS selfservice app slow

[elrobbo]

Goodmorning! ( for western european viewers )

i having trouble finding a solution for my problem. When users start there DEP IPhone, the whole enrollment proces is smooth and fast. But when they start the selfservice app, the waiting starts. It takes forever to load and i can't find out why this is so slow. ( sometimes hours )
We have around 80 apps in our store.

1. JAMF Cloud
2. IPhone 7
3. 300 IPhones

4. 80 apps

   It's important because we have limited time during the rollout. We are forced to create a itunes account during the rollout, because it just takes to long to fill up the local store.
   It doesn't make a difference if we use WIFI or 4G.

Any ideas for me?

Thanks a lot!