I have a LAN-to-LAN vpn tunnel issue. Basically this connection has been working fun up until last Sunday evening. Monday morning rolls around and the site is no longer able to send any packets larger than 538 bytes (payload).
None of my other sites beyond this one have any issues with the same config attached. The site is connected via an Ambit cable modem from Time Warner (business class service).
TW of course claims there is nothing wrong with the service. I have replaced the hardware at the site, and even reconfigured the original hardware to test the tunnel here via DSL and it works fine without issue.
So, ICMP works fine until you tell it to send something larger. Services such as RDP do not work at all.
It appears to be a fragmentation issue. Suggestions on where to start? DF bit is set to clear, MTU and MSS sizes have been adjusted. Config for device is attached.