@wtowens207 A client might be asking for that... I am not aware of anything in pfsense that would be looking to download the wpad.dat file.. What packages do you have installed?
I believe this has something to do with the proxy, but I'm not running a proxy on my firewall.
So you have a proxy internally? It could be trying to download that from your host, and yeah if your host says hey this source IP is bad, block it - then sure all your connections from pfsense would be blocked, ie all clients behind it, etc.
Or it could just be some other client behind pfsense trying to download that..