Websites For License And Lease Renewal Working On Mobile, Giving Errors On PC?

I'm currently attempting to file some renewals online, namely through the DMV and my rental payment portals. I'm repeatedly being given error messages when attempting to start these processes on my PC, yet they load fine on mobile. The websites themselves load fine on PC, it's only when I go to start the renewal process on either site that I get errors.

If it were one site I wouldn't think anything of it, but for this to be happening across two completely indepent sites for totally separate processes is puzzling me.

I'm on Windows 11, using Chrome (though I have tried Edge only to run into the same errors) and I've attempted disabling all extensions and reseting my settings. I have Windows Firewall enabled, with no alerts active. My IP and DNS server assignment are both set to Default (DHCP).

I've attempted restarting, fully shutting down, disconnecting and reconnecting to my wifi network and nothing has made a difference. I've had the same PC (self-built, no hardware changes in that time) and ISP for over 2 years now and have never encountered this issue previously (also doing renewals through these same sites in previous years on this device, on this network). I've encountered no other issues or complications with anything else I've done on this computer.

I'm exasperated trying to figure this out. Does anyone have a clue what this could be?