laravel new fails every time, uninstalled/re-installed laravel, still no help [MacOS]

This happens every time (except for the first) that I try to create a new Laravel app:

$ laravel new fred
Crafting application...


  [GuzzleHttp\Exception\RequestException]
  cURL error 56: Recv failure: Connection reset by peer (see 
http://curl.haxx.se/libcurl/c/libcurl-errors.html)

MacOS Sierra 10.12.5. I went through the Laravel installation process a few days ago, all good. Brew installed, Composer installed, Laravel installed, Valet installed. Then in the meantime I've been doing some other work with MAMP. Come back to Laravel to work through the tutorials (the 'blog' app) and it all goes fine. But then I try to create a new Laravel app, and I get this GuzzleHttp request exception every time.

Uninstall Valet. Uninstall Laravel. Reboot. Reinstall Laravel. Same thing.

I know I know it's a newbie issue, but I would have thought that a complete uninstall and re-install would make it work. But it doesn't.

The "-vvv" on the "laravel new" just says that there is a specific line within the GuzzleHttp that fails, but my machine is not unable to connect to the Internet, websites, etc.