|TCP 445 is Windows file sharing/RPC port. I do NOT recommend forwarding this to your server as it leaves it wide open for exploits, will slow down your server because everyone and their brother on the Internet will be trying to hack your server when they find out the port is open, and it defeats the purpose of trying to use a VPN for secured communications anyways.|
RRAS is tricky and sometimes it can intermittently work and not work even if everything is not setup correctly. One, most importantly, is the router where the server is have the ability t forward protocol 47 (GRE) to the server?
Another thing, are the subnets at both end different? (Example, is one 192.168.1.x and the other 192.168.2.x?) It helps to have them different. If they're the same, routing between the endpoints may get confused because they both "look the same". If they're different, the router know clearly which end is which.
Last, the link below is to a posting I made a while back when I had difficulties getting RRAS on Windows 2003 Server to work. It has some suggestions and links that may be helpful. Good luck.
Assume that I already did an Internet search.