VPN tunnel connects, but not Exchange Server

[jeffcarp]

I am having a problem connecting to our Exchange Server once my VPN tunnel has been created. This is only a problem on my home's wireless router. It works fine on my Verizon Aircard. Once I establish the VPN tunnel, I can browse the Internet without issue and can access network drives. However, I cannot connect to the Exchange Server through Outlook. Outlook cycles through "attempting to connect to Exchange server" and "Disconnected." As I mentioned, if I disconnect from my wireless connection and connect to my Verizon Aircard, I can connect to Exchange server without issue. I have not had access to other wireless networks to know whether it works on other wireless networks. I've read that Outlook / Exchange through a VPN tunnel is sensitive to MTU issues. As I browse the registry, I don't see any MTU values higher than 1500, some settings show 1300. I see that my wireless router has a "fragmentation threshold" setting which is the default of 2346. My wireless card on my laptop has a similar 2346 setting. Could that be related? The WAN status in my wireless router reports an MTU setting of 1500 from my ISP. I have confirmed that IPSEC, PPTP and L2TP are all enabled in my wireless router. Any thoughts on where I go from here? Thank you.

[jamesk1792]

I'm by no means a guru in the networking world, but my organization sees this daily. We are required an MTU of 1300 on everything that is trying to VPN in, in order to get Outlook to function correctly. Our logon script to map network drives will fail as well without setting to 1300.

It's the tell tail sign of problems on our trip locations.

Put your MTU at 1300 on your VPN client virtual adapter and on your nic on the workstation/laptop. I wouldn't be suprised if the issue resolves.