Big Sur 11.3.1

Can the computer surf the Internet without this error message outlined above. If Yes, how is the computer being used to download Big Sur 11.3.1 ? What version of macOS is presently installed ?

Sometimes the error messages are not too clear so one might try this Method below;

Shutdown Router. Shutdown computer and disconnect all External Drives. Restart Router. Connect to Router via Ethernet Cable. If via Wifi - Disconnect all other Devices using the Wifi - want the Maximum Bandwidth only for this computer. Restart computer in Safe Mode. It does a Repair Disk, Clear System Cache files and only loads Apple Software, extensions and Fonts. Will load slowly - Normal. Once Logged in - open Apple Apps Store and Get the Full Version of Big Sur. It will take some time and several pauses will occur - normal. Countdown clock may say 15 minutes but in Real time may be 30 minutes. Same goes for clock at 10 minutes could be 20 minutes in Real time. Eventually , Full Installer will download and a New Application in Applications Folder will present called Install Big Sur. Stop there and perform a Time Machine Backup. If desired - have an External Drive - Copy & Paste the Install Big Sur Application to external drive for future usage - making a Bootable Installer. Now run the Installer.

Have found this method more reliable than the Software Update which is very iffy at best.

Have a Theory or Rationalization - because Apple is in Transition from Intel to all In-House M-CPUs - there are issues supporting both Intel and M1 or M2 CPUs especially of updates to Big Sur. Thusly, the growing pains being experienced by many end Users. I remember when Apple was transitioning from G4 Motorola CPU to Intel - similar but not same issues were occurring.

As for Fifth Wipe and Re-install - would suggest getting the Full Installer - Create a Bootable Installer of Big Sur and boot to it ( Bootable Installer ) and Wipe the Entire Drive 100% Clean - nothing on the drive - then do a True Clean Install. Have found this more effective than anything else. No left-overs to bugger things up. Also, do not do a Migration Assist as that may re-introduce previous existing unresolved issue.

I'm on a Macbook Pro, 13", 2018, Catalina v.15.7. Have been trying to install Big Sur for 2 days. It gets me as far as 9 seconds remaining on the installation and then immediately says I have no internet connection. Thoughts? Help?

My 2017 MacBook Pro 15" w/ TouchBar has fans blazing with 15 minutes remaining on the 11.3.1 update -- and absolutely no movement or progress whatsoever. Just stuck.