Changes

===Background information===

===Background information===

VPN uses port 1723 and protocol 47.  

VPN uses TCP port 1723 and protocol 47 (GRE).  

In server & gateway mode your modem should be configured in bridged mode and automatically forwards all traffic to the server.

In server & gateway mode your modem should be configured in bridged mode and automatically forwards all traffic to the server.

In server only mode, your router must be configured to forward port 1723 to your server and must provide full support for protocol 47. Note that protocol 47 (GRE) is not a port and therefore you cannot forward it. Not all routers support this protocol so VPN is not always possible in this network arrangement. In order to make pptp type VPN connections in this network arrangement, the router specification must clearly say that it can handle passthrough pptp VPN connections. Note that the routers at both the remote and local ends of the VPN pptp connection must be able to handle pptp VPN passthrough for this scenario to work correctly. Check your router specifications carefully. Errors in your log files may indicate that one of your routers may have a problem forwarding GRE packets. If you see LCP timeout errors in your log files, there are many possible reasons. The most likely one is that a firewall somewhere between the two ends is blocking/dropping GRE packets.

In server only mode, your router must be configured to forward TCP port 1723 to your server and must provide full support for protocol 47. Note that protocol 47 (GRE) is not a port and therefore you cannot forward it. Not all routers support this protocol so VPN is not always possible in this network arrangement. In order to make pptp type VPN connections in this network arrangement, the router specification must clearly say that it can handle passthrough pptp VPN connections. Note that the routers at both the remote and local ends of the VPN pptp connection must be able to handle pptp VPN passthrough for this scenario to work correctly. Check your router specifications carefully. Errors in your log files may indicate that one of your routers may have a problem forwarding GRE packets. If you see LCP timeout errors in your log files, there are many possible reasons. The most likely one is that a firewall somewhere between the two ends is blocking/dropping GRE packets. Some routers/gateways automatically forward GRE when required, by watching the negotiation on TCP port 1723.