What is 192.168.100.7?

What IP are you pinging from?

Which adapter is that subnet on?

I recommend not using Net networks in VBox unless you have no choice, it makes everything much more complex.

Steve

So your on-prem Webserver is also running as OpenVPN client which is connected to your gcloud pfSense? You are only running this one pfSense? What is your OpenVPN mode?

-Rico

pfSense should not have a LAN gateway. If you have that set on the LAN interface remove it.

Then go to System > Routing and make sure the WAN gateway is set as default.

The fact you are able to reach the webgui shows it must be working to some extent.

Steve