I am experiencing a very bizarre problem, and cannot seem to determine the cause. I noticed today that Outlook 2010 was sitting on "downloading OAB" for a long time. I have seen this before, so I started checking the usual suspects like permissions on the OAB folder on the CAS servers, etc. I have done a lot of searching and find plenty of examples of people having issues with Outlook Anywhere not working, but non experiencing the opposite.
So here is the scenario:
I attempt to download the OAB when connected to the LAN via VPN and it just hangs, but doesn't throw an error (don't know if I waited for hours if it would or not). As soon as I disconnect the VPN (software), Outlook will connect again, and the OAB will download no problem. I first discovered this because I was testing the issue using a test account on a PC not connected to the LAN, just the internet.
I could consistently replicate this, and the same results persisted even after isolating specific cas servers in the array.
I suspected that this was a VPN issue, so I remoted into a PC directly connected to the LAN at the datacenter where the servers reside. I experienced the same exact issue after setting up an account. It would hang on downloading OAB.
I have tried rebooting all the CAS servers, no difference. I have checked the folder permissions, no problem. I can connect to the OAB using a web browser on all cas servers, and both remotely and on the LAN.
I have Tested autodiscover over LAN, VPN, and HTTP, and they all come back perfect, no difference between the two. (using the tool built into Outlook)
I also checked the internal DNS to make sure it is resolving correctly.
I have tested this with several accounts/users and it is the same experience. Additionally I have created new profiles, and everything loads up until the OAB. If I drop off the LAN and go http, it completes.
As far as the CAS Array, we are using WNLB, there is no hardware load balancer or anything.
This install has been in place for nearly a year without issue, and no changes have been made recently to the configuration like RU's or Service packs.
All I can think is that something is causing an issue in communications internally that is being used between the client and the server. Are there different communication protocols being used depending on if OA is being used vs LAN?
Any recommendations for troubleshooting would be greatly appreciated. I am completely stumped.