I was troubleshooting a SonicWALL Global VPN Client problem today. When viewing the log it kept saying “The peer is not responding to phase 1 ISAKMP requests”. I found the following SonicWALL tech note and verified that all of the settings were correct. I then had a co-worker try connecting from our office with his client (since I didn’t have it installed) and he was able to connect.
At this point I decided to reinstall the client, coincidentally a new version of the client was released today so I downloaded and installed that one rather than the version that was previously being used. After installing the application launched and the Windows Firewall asked if I wanted to unblock it which I said yes to and proceeded to configure the client and was able to connect successfully.
So basically if I had added the Windows Firewall exception before uninstalling or disabled it all together the VPN client probably would have worked. Just wanted to post this in-case you run into the same problem to check the Windows Firewall.