↓ Transcript
Technician: ...try it again. It should work now I've done that.
Customer: It does... Why did it go wrong in the first place.

Technician: (thinks) Well, your organisation has a limited scope for allocating IP addresses through DHCP and the introduction of 32 new iPads and re-allocation of 57 laptops formerly off-site, plus the quantity of unauthorised personal devices on the WiFi meant that it couldn't get the server to allocate an address, leaving it on a 169.254...

Technician: (says) A recent Windows update probably nudged something...