Windows 10 VPN server appears to be listening but not connecting with a GRE protocol 47 error.

[WarrenNeufeld]

For no reason I can identify, my PPTP W10 VPN server no longer accepts incoming connections. I consistently get the following Event ID 20209 Rasman message in Event Viewer.

A connection between the VPN server and the VPN client xxx.xxx.xxx.xxx has been established, but the VPN connection cannot be completed. The most common cause for this is that a firewall or router between the VPN server and the VPN client is not configured to allow Generic Routing Encapsulation (GRE) packets (protocol 47).​

My router has VPN passthrough enabled and the router log says the request is being forwarded to port 1723. My Norton Online Security firewall has protocol 47 enabled. Yesterday, with netstat, I got the following result.

netstat -an |find "1723" /i
TCP 0.0.0.0:1723 0.0.0.0:0 LISTENING​

However, today the same command returns nothing. Just a blank line with a blinking cursor after leaving the PC on all night and when I reboot. A power down/power up, however, provides the first result: TCP 0.0.0.0:1723 0.0.0.0:0 LISTENING.


I suspect this incoming connection problem is related to an update installed while I was sleeping but cannot be certain.

Any suggestions?

Bob

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