Recently I overwrote the whole hard drive with zeroes [dd if=/dev/zero of=/dev/sda]. When I booted from a LMDE18.2 USB disk created using rufus.exe on a Win10 library computer [reimaged after every user] the Network Manager remembers previous settings. That is it tells me I have a current connection and the ethernet settings show the MAC address of my laptop AND as well an ethernet over powerline option. I used both of these at home, but I am now at the library when it is reporting this connection.

Anyone experienced this before? How on earth is it "remembering" a prior EOPL setting?

The only other oddity is my DVD drive stopped working along with other devices when I believe I was hacked. The other devices drivers were reinstalled ok. I know it could be I need to find the driver, it could be coincidence etc. Is it possible for the DVD drive to be firmware root-kitted? That is, it is loading these ethernet settings?

Just wondering if anyone has experienced or knows anything about this. [The driver for the laptop is very difficult to find]. The DVD drive does spin and lights up on booting, and Win10 also doesn't recognise it.

Network-manager remembers every connection it makes. Yes, and firmware-bearing component can be bricked by software. But I doubt it has anything to do with network-manager. I'd just exchange the drive for a working one.