Today, I was trying to connect to our VPN with Ubuntu 11.04 and found out that was not working. Well, after a bit searches on Google, I found out there are some points of VPN settings that I needed to change.
Tricky VPN settings on Ubuntu 11.04
  1. Username should be domain\username.
  2. Do not fill out domain in the VPN configuration.
  3. Under the advanced option make sure you tick "Use Point-to-Point encryption (MPPE)" option. (see above screenshot)