Comment by rconti

I reinstalled MacOS on a 2011 MacBook Air and it was actually shockingly hard. Thankfully, my machine booted and worked fine, so I didn't need to create a bootable USB stick. From memory:

  - Network recovery boot cannot connect to your wifi because reasons. It'll see the SSID, but won't even prompt for password. It's totally unclear why nothing is working.
  - Fall back to old IOT SSID with ancient protocols
  - You cannot directly download or install High Sierra (the latest supported OS) for reasons I don't remember. 
  - I can't remember how, but somehow you can install Lion
  - Launch beautiful Mac desktop. App store won't work because the certs are too old, or something. Safari won't work, because the supported SSL protocols are too old. 
  - Use a modern Mac to download a DMG installer for a slightly newer OS
  - Copy it to a USB stick
  - Find a USB stick big enough to hold it, try again
  - Plug USB stick into target Mac, copy installer to desktop, run it
  - Now you have a more modern OS that can actually connect to websites
  - Also teh app store works, so you can upgrade to High Sierra using the app store.

But yeah. Man, the desktop was so beautiful and refreshing.