I’ve managed to get the m0n0wall setup to allow IPSEC lan-to-lan connections from some Vigor 2710 after much trial and error as google and the m0n0wall forum doesn’t seem to know much about the Vigor 2710.
The setup isn’t hard, my main mistake was to use a PSK generator for my pre-shared key which put a bunch of different unusual characters in the key. The key caused me hours of fault finding as it didn’t occur to me that it could be the issue until I had almost given up and tried a simple 123password4321 key just to see and hey presto the tunnel sprang into life!!
Here’s a example setup for the Draytek 2710 and the m0n0wall below (though IP/Domain names have been changed):