When computers both internally and remotely try to VPN into my server that is running Windows Server 2003 R2 Enterprise Edition, they receive VPN Error 800: The remote connection was not made because the attempted VPN tunnels failed.
I pinged my server and it replied all 4 times.
I went to CanYouSeeMe.org (on my server) and received the message: Success: I can see your service on 18.104.22.168 on port (1723) Your ISP is not blocking port 1723
I verfied that remote access permission was still enabled for my users in Active Directory Users and Computers.
I have changed nothing on the server in the last 2 months and VPN was working fine as of yesterday.
The image I uploaded is from my laptop which I verified that PPTP VPN and ESP Protocol were not being blocked by my AVG firewall.