D-Link → [Help Me] anyone have DI-624 working w/cisco VPN client

I'm on my third generation DLink wireless router and was happy until I switched to a DI-624. I had a 614+ that was working flawlessly with my VPN client (stupidly, I gave this one away when I upgraded to the 624).

I now have a 624 (version B2 with firmware 1.25) that works great until I start using the Cisco VPN client (tried versions 4.0.2b through 4.0.3a). I can successfully connect to the VPN server and run very well for anywhere from 10-60 minutes until the DI-624 reboots, killing my VPN connection. I've tried logging the traffic but the 624 log file is not preserved across reboots. I've verified that the only time the 624 reboots is when I'm using the Cisco VPN client. When not running the VPN client, the router has worked flawlessly.

I've called DLINK tech support a number of times and get no help, although they are friencly (the typicall firmware questions, did you do a hard reset, did you remove any other devices, etc, etc.., all of which I've done a number of times). I'd at least like an admission that there is a known problemand that they've seen and are working on a solution, otherwise I've got to resort to getting the Linksys router which I know works with the cisco VPN client

Can anyone out there help?

Use SetMTU to lower your MTU settings. If you want to test your MTU, do this:

ping -f [do not fragment] -n [number of pings] -l [size] destination ip address

C:\>ping -f -n 1 -l 1472 x.x.x.x

Where x.x.x.x is a valid IP address on the (internal) remote side of the VPN.

Reduce your -l option from 1472 until you don't get this error:
"Packet needs to be fragmented but DF set."

You may want to reduce by increments of 20-30. After you get successful
pings, increase your -l option until you have the highest number that
successfully went though. Add 28 to this and this should be your optimal MTU
setting.

Adjust MTU settings accordingly and reboot computer.

Doesn't seem to have helped.

I tried doing the above. My router MTU is 1492. I reset my Dell Truemobile 1150 MTU to 1500 and I went through the process you describe (after rebooting, etc of course). Ended up with no dropped packets at a setting of 1272 so I set my MTU to 1300.

As before, I can connect and successfully run all applications for a period of time (5 minutes to 1 hour) and then for no apparent reason, the router resets. I can't capture the traffic that causes the router to reset because logs are cleared.

In the router config go to Tool>Misc. Enable the option to discard ping from the WAN port. This will usually greatly increase the router's stability.