Android clould testing with VPN support [closed]

We are having our own little farm of Android phones which we are using to test our app. We would like to outsource this to a third party and use some of the many cloud testing services.

However, in contrast to the typical use case our server backend for the phone is not (and can not be) a public endpoint on the internet. Therefore we need this cloud testing service to support setting up a VPN connection on the phone it is testing on.

I have been looking around, but have been unable to find a service which supports this. Is there such a service out there?