If you're unable to reach the pfSense webgui that sounds like either an issue LAN side or some routing conflict, like maybe your modem lost sync and came up with an IP the same as the LAN subnet?

Did you try connecting out from the console directly?

That's what I would do, determine exactly what is failed so:

Check the interface addresses, at the command line: ifconfig -a

Try to ping out by IP address and by fqdn.

Check the routing table: netstat -rn

Steve