Woke up this morning, switched on the computer - no network connection. (Well, only my VirtualBox Host-Only Network, but that doesn't get me onto the Internet.) As in, it didn't even recognise that there was a network hanging off my network adapter, not even a LAN.
Took the network cable out (not easy in the confined space in that part of the case!) and put it back in - no dice. Looked up Driver Manager - no yellow exclamation mark. Disabled the network chip and re-enabled it - and things worked again.
Still, I hope it's not going to make a habit of that.