I have ages ago on my previous work laptop manually configured DNS addresses, for home usage when I was home at corona times. After some time, I stoppped using those DNS services, and later I noticed that when I switched Wifi or WLAN on, it defaulted to use those DNS addresses.
As my user account is not a local admin, I have to open network properties, and go to change adapter options, open up properties of Wifi device, and revert to DHCP resolval of DNS addresses instead of the hard coded values in the field.
Now, years later, I have switched work laptops. The problem still persists. Whenever I open Wifi, or WLAN, be it at work or at home, something sets the hard-coded default DNS addresses. Internet won't work, and I have to manually clear it again, logging as local admin account to do that.
What could be setting these DNS addresses when I turn on Wifi? It seems to only persist through the current day, or so. If I shut Wifi, and turn it back on without locking, logging off or anything, it still remembers the default.
It is still a nuisance, since mostly I work with Ethernet cable, but every now and then, few times a month, I try to use Wifi and each time, encounter this issue.