Here are the errors you will receive if your router does not have VPN pass-through enabled:
- iPhone :
- VPN Connection
- The PPTP-VPN server did not respond. Try reconnecting. If the problem continues, verify your settings and contact your Administrator
- Windows (using VPN Utility):
- DotRas.RasDialException: The remote connection was not made because the attempted VPN tunnels failed. The VPN server might be unreachable. If this connection is attempting to use an L2TP/IPsec tunnel, the security parameters required for IPsec negotiation might not be configured properly.