OPC UA over VPN-Tunnel|OPC UA Standard|Forum|OPC Foundation

Hi,

I Am working on a project where the OPC UA Server (Phoenix contact AXC 1050 PLC) is connected to a Sierra RV50 router with a M2M Sim-Card (Router 1).
The OPC UA Client is a laptop with TIA Portal WinCC professional on a office-network (Router 2).

So I know that I Should put the IP "opc.tcp://name:Port" of the PLC (OPC UA Server) in the "OPC UA Discovery URL" in TIA Portal Scada (OPC UA Client.)
But this won't work because the PLC is on another network. 

I found something that it should be possible to connect the 2 networks with a VPN-Tunnel. 
But now my question is, 

Is it possible to send and receive data over a VPN Tunnel with OPC UA?

Hope to receive a reaction.
Thanks in advance!

Joost