Thanks Jimp,
Unfortunately I don't have a crypto / accelerator card in the PFSense machine. It's a Dual Core HP XW4600 workstation with a DLINK DFE570TX card for the WAN / LAN.
I have tried just about every configuration I can think of, have remotely controlled the Watchguard and checked, the settings are identical in every way. I can never get passed that last message.
I have successfully set up an IPSEC VPN tunnel between this box and a couple of Draytek Vigor boxes, just can't get the Watchguard Firebox to talk.
If there is someone out there in the UK that has done this I would be more than happy to pay them to sort this out. I just need to get it up and running else face having to split my network out with a router in front of PFSense and have the client drop their own Watchguard box into the mix.
Thanks
Graham