IPSec MTU Issue - Only from Windows 8

[Phonebuff]

Have a FreeBSD based Host behind a pfSense 2.4.4 7100 and I have a Win 8 workstation behind a 3100 2.4.4 that was just updated a few days ago.

They are connected with an IPSec tunnel and I can ping and SSH across the tunnel with no issues.

The Windows Box can however not receive a Screen from Nagios and the pcap onfrom the 3100 side indicates it's a MTU size issue with the Don't Fragment Flag set.. I am also getting an error when I try and ping with a larger packet from the Windows 8 box.

C:\Users\jms>ping 172.17.128.127 -f -l 1500

Packet needs to be fragmented but DF set.

I do have Enable Maximum MSS Checked and the Size set to 1400.