I have a 18 site VPN. All remote offices connect to the head office. Currently there is a 2800 in place. We now have two internet connections at the head office so I have installed a 2820.

VPNs from the remote 2800's work fine except for one which runs firmware 2.6.1.1_D794214. I will upgrade this but know from experience that upgrading from this firmware wipes the device clean or at least looses its config so I will to go out on site to perform this update. I guess this is the issue anyway since all over 2800 seem to work ok. This is also an odd one as the VPN establishes but no data can be transferred. Stats show TX and RX to be 0 at all times.

I also have four sites that have old 2600's. All four of these refuse to establish a VPN to the 2820 (firmware 3.3.1.2).

Any there any work arounds? Is this a known issue?
I have currently put the old 2800 back in at the head office and again all is working.