To create a tunnel between these two devices you will note each has varying settings but not all line up. You can try and mess about with settings and eventually it will work, so I decided to post what we use to setup the tunnels and help save that bit of time.
The key issue we run into is for Phase I, on the Watchguard you must disable NAT traversal and ENABLE IKE Keepalive. Otherwise you run into the non-matching IPSEC errors, even though all the encryption settings are correct. Once you have this set, the rest is up to having the standard encryption settings match on both sides. Not too bad huh? Though if you aren’t aware of that it makes things much harder. The encryption settings pictured were just what we had set for testing, use what you like and hopefully it will be 256-Bit+ :)
