VPN Pass-Through on Linksys

[Fraz]

I've been trying to get a VPN connection running through a Linksys router on
a 2000 RAS server, but the best result I could get was to the verifying
username and password stage then it would stall out with an Error 721. At
any rate, I just updated the firmware on mine and now I can connect. Just
wanted to pass along the tip.

 

[Sharoon Shetty K [MSFT]]

This is usually caused by the router (or some other router/firewall in
the path) blocking GRE. The encrypted VPN data travels as the payload of an
IP packet with a GRE header. If anything blocks GRE in either direction, no
data will flow and the connection fails. GRE (Generic Routing Encapsulation)
is IP protocol 47.