Firebox SOHO 6tc dropping VPN

I have a pair of Firebox Soho 6tc's located in different places in the country VPNed with a few AxxisAC300 firewalls.  For some reason, the VPN tunnel between here (Axxis) and one of the Soho 6tc's keeps dropping over and over, forcing me to manually disable the VPN setting in my firewall here and re-enable it to rebuild the VPN tunnel.  What's really wierd is the link between that Soho 6tc and A DIFFERENT Axxis (in another location) never drops.  It's the same brand/model device as here.  A temporary solution to route through that Axxis box, so now the users behind the Soho 6tc are being routed through an extra VPN hop just to get to here.  Since an exchange server is located here I have no doubts it will negatively impact performance, but I can't think of another solution.  All firewalls have the latest firmware and all are configured correctly.  The VPN keeps dying.  Eventually the plan is to replace all Axxis firewalls with Fireboxes (the one here will be replaced with a Firebox x700) so I'm sure Firebox -- Firebox VPN will be very stable.........but until then I need a solution that will save me from having to rebuild the VPN tunnel almost every day (sometimes several times per day) without having to rely on a multihop VPN schema.

Lots of points so go for it :)