I had the exact same issue with 2.5.1; trying to run Gw2Gw VPN from my home through a semi public wireless network to the office to get internet access.
The solution was for me to put in OPenVPN Server's Advanced settings; under the Global push options:
Push this Networks:
0.0.0.0/1
128.0.0.0/1
And under Push these nameservers:
The Green IP of your Endian VPN server
Hello! Sorry for my really bad English and to revive old topic but I found a solution for this problem.
the first thing you should do is define what you want to target DNS in the internal domain, then I am connected to VPN interface (on the server where the drawback EFW) enter proxy> DNS> DNS Routing and add a name server for your domain
Field 1(domain): domain.local #(your domain)
Field 2(DNS Server):192.168.0.1@tap1 #(your dns server on the LAN @ interface tap1)
I hope you find it useful