@jonathan66
Reboot using the console.
Chose option 5.
When asked, use option F = Reboot and run a filesystem check
After the reboot, the file system is checked and repaired.
Changes are these files :
/usr/local/lib/php/20190902/zlib.so
/usr/local/lib/php/20190902/xml.so
will not get repaired. Maybe even removed because invalid.
A re install is in the case the fastest way out.
Or, from the install file - extract these two files and copy them over.
What happens is that your config file can't be read, so pfSense defaults to default settings.
For WAN, this is DHCP on WAN - so it works out of the box.
For LAN it is 192.168.1.1/24 etc - but you probably changed that, so LAN does not seem to work now (tip : keep LAN to the default settings, so, in case of emergency, LAN works ^^)
Btw : tip : before you upgrade, reboot using the console and do a "sanity" file check. That way you are sure all is well. Check the GUI logs after the reboot. See for any suspect messages.
File system inconsistencies go undetected while booting from the GUI (except when the block the booting process).
They are normally introduced when there is a power failure (aka : no clean shu tdown) and very comparable what will happen with your PC when you ripe out the power.