I copied my Steam folder from my laptop to my PC in my attempts to try and get some of my games to work offline. I followed this answer in regards to editing the
loginusers.vdf file but when I went to try and see if it worked Steam went to search for an updates, failing to connect to the internet and saying that Steam needed a network connection. correct me if I'm wrong but quite sure that's the opposite of being offline.
Before copying my Steam Folder I did boot up Steam just to make sure there were no updates pending for it so at the time of copying it it was up to date and I can't just connect my PC to the internet as it's too far away from the router for an Ethernet Cable (and there's ~6 years worth of Windows/Misc Program Updates since this PC has never been connected to the internet since I first got it).
So how can I stop Steam checking for updates for an offline machine?