I'm trying to create a home VPN on Windows 10 using a Netgear N600 router.
All goes well, setting up the host and client, up until connection time. I receive an error that states the host is not configured to accept GRE (Generic Routing Encapsulation) packets on Internet Protocol 47. It says that opening IP 47 might help. But how does one do that? I can't find any setting within the router to open it. Is this a port, and therefore can it be port forwarded? (I'm guessing that it is not a port because port forwarding 47 did not make any change.)
Best Answer
No, it's not a port. It's one layer down from that. It's an IP Protocol Number. For example, TCP is IP Protocol Number 6 and UDP is 17.
If the admin UI for your router doesn't mention protocol number forwarding anywhere, try making your VPN server the "DMZ host" or "Default Server". Different products call it different things, but it basically lets you specify one machine on the private LAN side of your router to which your router will forward all new incoming traffic that the router doesn't know what to do with (that is, that it doesn't already have a static or dynamic mapping for). Most routers I've worked with will forward packets with unknown IP protocol numbers to the DMZ host.
Note that GRE is used for PPTP style VPNs, so see if any of your router's PPTP VPN gateway/pass through features/settings can help or hinder you.