A Windows XP PC!

This customer was looking for help with connecting their Desktop PC to their WiFi. Upon viewing the device, we were found that it's still running Windows XP from 2001! As Windows XP has not been receiving any security updates since 2014, connecting the device to the internet makes it easily vulnerable to malicious connections even without browsing the internet. So we convinced the customer to upgrade to a newer device that we later procured and setup for them.