My 2017 iMac has not been able to install Big Sur out of Catalina without getting hung, after multiple different attempts. As such, I've completely wiped the internal drive, excepting only the recovery sectors. As such, all connectivity configurations are lost and the machine needs to literally install from scratch.
This is the problem with relying on internet access for major updates.
iMac 27″, macOS 10.14
I erased the entire drive; all three 'volumes', leaving only the Recovery volume on board.
The question, therefore was how to get a machine that wouldn't upgrade to Big Sur to access the installer and internet for the upgrade AFTER wiping the entirety of the drive.
I went about it the hard way but I finally resolved the issue by taking a Time Machine backup off of an Apple Silicon iMac, which let it restore to Catalina but cleared whatever was blocking the upgrade. Said machine is now running Big Sur.
Just to make sure. Are you just making a statement or asking for how you can attempt to install macOS updates without an Internet connection? Which exact "wiping" procedure did you follow? Would it be this one? How to erase your Intel-based
Mac - Apple Support
If it is the former, I suggest that you submit your concern directly to Apple here: Product Feedback - Apple
If the latter, the support article you came here from should provide the answer.
What if you've wiped the drive and the machine is no longer connected to the internet?
