What is VPN pass-through ?

First, if you haven't already, disable any pc firewall while troubleshooting the VPN connection. Once you are sure that the firewall is disabled, proceed below. Firewalls cause the same errors as lack of PPTP passthrough on the router, so to test this you need to be sure your pc based firewall is off.

PPTP passthrough is a setting/feature on routers which is required in order to connect to a PPTP VPN account. To understand how it works, we can go over what happens when you connect to the VPN from a client PC.

  1. PC sends request to VPN server
  2. VPN server replies to this request
  3. If PPTP passthrough is disabled or not supported - the reply reaches the router, but the router doesn't answer or refuses the request.
  4. If PPTP passthrough is supported and enabled the reply is forwarded to the client that started the request, and the connection establishes successfully. (note that a local PC firewall will block it at this step) The first thing to check is your router's documentation. It should state whether the router supports PPTP passthrough and explain how to enable it.
  5. If you cannot determine if your router supports PPTP passthrough we can test this by having you connect your client PC directly to your modem and then attempt the VPN connection. If the connection works with the direct ISP connection it will isolate the problem to your router and most likely it's PPTP passthrough abilities. Setting your client PC to be in your routers "DMZ" may work around the problem for one client PC on your LAN. Another possible solution would be updating your router with the latest software from the manufacturer, it's possible that updated router firmware will fix or add pptp passthrough, you may want to check at your router manufacturer's web site for any fireware updates to apply.
  6. If the connection fails even when you connect directly it could mean that either your ISP doesn't allow PPTP VPN connections. In this case our OpenVPN service should allow you to connect.

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