Good afternoon.
Thank you for your submission.
The firewall settings were automatically added to the device after the correct creation of the VPN.
You only need to set up SNAT on the Drytek router. How to take SRC 88.88.88.88:8080 as DST 192.168.7.250.
Since the router itself has a route to the subnet on the reverse side of the tunnel, and will know where this host is located.
Thank you.