Photon not work on VPN?

Hi I am working on an existing multiplayer game.

The point is:

The game work correctly, but on VPN the game do not work.

I get this error:

DNS.GetHostEntry() failed for: Exception: System.Net.Sockets.SocketException (0x80004005): Could not resolve host ''

Any soloution of how to solve?

Ads work correctly, so the problem is not exactly internet...