These instructions will show you how to configure ExpressVPN on your pfSense device, using a pfSense OpenVPN setup.
Assumption you are configuring your network for a generic 192.168.1.0/24 network setup.
There are multiple parts to this:
If OpenVPN is connected to the server but you can't access the Internet.
After connecting, if you can't reach the Internet, it's likely that your setup has one or more of the following problems.