If stuck on the Preparing for Update screen, also check your network adaptors. I have a VirtualBox installed which installs a virtual network adaptor. In my case the updater was trying to use this, setting it to disabled resolved my issues.

Might be an issue for devices where there are VPN, secondary adaptors etc.

Check in Network and Internet > Advanced Network Settings.

Lounge: DSP33's, MS200, QNAP (Storage and Core), G68D, HD421
Family Room: DSP5000
Kitchen: F80
Portable: Explorer2