A couple of months ago I set up our president's laptop to VPN into our
network through our BM 3.7/3.8 servers. It worked for a while, but no
longer does so. When he tries to VPN into the network he gets the error
message, "Failed to connect to the authentication gateway. Either is an invalid VPN server address or the authentication
gateway is not loaded on the VPN server."

I know the problem is on the client side, because other users can VPN in

If I try to telnet into the BM servers from the laptop using port 353 or
80, I get no response.

Interestingly, when I gave the laptop a static public IP address that put
it on the same public network as the BM servers, the VPN login did work.
I seems as though the VPN client is having difficulty with connections
that must traverse a router to reach the BM servers.

On the laptop, I have turned off all firewalls, antivirus software, etc.

Any thought on this?