Why is there no VPN PPTP connection?

Question

VPN

Hello, I've run into this problem. There is an Asus rt-n65u router with padavan firmware installed. I set up a VPN server on it: PPTP, MS-CHAPv2 authentication, MPPE-128 encryption, MTU 1450, MRU 1450. The vpn connects to the local network and works fine. (that is, by 192.168.1.1), but if I try to connect from the WAN, it does not connect and writes an error 800. I turned off the browser on the PC, turned off the built-in firewall on the router, and also turned off encryption does not help. Tell me, what is the error, why can't I reach the VPN from the WAN? Will this article suit me habrahabr.ru/post/216101 ?

Answer 1

As I understand it, the PPTP server is in the LAN.
From the outside does not cling.
We need to find out what's going on with the GRE traffic.
PPTP uses the GRE protocol to transfer data. Which is possible in the router should be slipped separately under NAT. Although linux should be able to do all this out of the box.
If it not in GRE the reason - that look can something confused with routing. The default route received from the vpn server, for example, can sometimes interrupt other routes, to the dns and to the vpn server itself, and accordingly, the packets simply stop going, because. they don't know where.