Windows MTU Adjustment

There are some times when you find yourself needing to do something that is not exactly what anyone would call a “best practice” to get something working.  This was one of those times.  I found myself in a situation where we were behind a device that is not a traditional “router” but does some encrypted tunneling.  We did not have enough equipment (or IPs) to just drop a router behind it, so we just dropped a switch and called it a day.  It seemed like everything was fine except Outlook.  The computers would join to the domain, open web pages and send e-mails just fine.  The inbox was completely blank.  This is something I think everyone shoots for, but it is a bit creepy after a day has gone by and there is NOTHING there.  After a bit of digging into the problem, one of the people supporting us mentioned they had this problem before and changed the MTU to fix it.

After opening regedit and navigating through what seemed like a million non-sensical different sections we finally got to where we needed to add some additional information.  Did not seem too bad at the time, but when I went to go back and do it myself, I gave up after about 5 minutes.  Finally, I did a bit of google engineering and ended up with this (which I think is significantly easier than going into regedit):

netsh interface ipv4 interface “Local Area Connection” mtu=1350 store=persistent

Hopefully you do not find yourself needing to do this, but in case you do this should help speed things up.