I just install DUDE and I have problems:

Computer IP: 192.168.0.x (assigned from VPN server)
VPN server: 192.168.0.x and Public IP: 88.85.112.x
Mikrotik ROS: 88.85.123.x

I can access to internet and Mikrotik (from Winbox), but.... Dude can not ping out from local network. It discovered local network, it is ok, but out from VPN server can not ping.

You can try to fix routes, so it is possible to ping outside from the network, where Dude server is connected.
Or you can consider about better location for Dude server.

The problem was firewall.

Sorry