Comment by greyface-
Were the autofilled DNS servers in RFC1918 private space (10.0.0.0/8, 192.168.0.0/16, etc.)? I had issues after the upgrade with Google Chrome being unable to access hosts in these ranges, and fixed it by going to System Settings -> Privacy & Security -> Local Network and toggling Google Chrome off and on again.
No, they weren't local. I have no idea where they came from. I couldn't even delete them, but when I added the Google servers, they autofilled ones were automatically deleted.