Why is my Mac unable to connect to network
After of literal hours of debugging, I discovered that Charles Proxy was not symptom of a broader problem, but rather it was the problem (even though I rebooted several times and Charles was no longer running).
After hours of debugging, I spent a little time mentally backtracking and thinking about when the problem first manifested itself, and remembered Charles. So, I decided to fire up Charles and the network was suddenly restored. And when I quit Charles gracefully, it restored everything to a stable state. Lol.
Clearly, when it froze on me, it left my networking configuration in some internally inconsistent state. But restarting Charles and quitting it gracefully allowed it to restore my computer to an operable state again.
That’s six hours of my life that I’ll never get back. I write this post to hopefully save someone the pain and anguish I just went through.
(FWIW, this is not a criticism of Charles. It’s an invaluable tool, like WireShark, for debugging networking code. I love Charles, but I guess one needs to be careful if it ever freezes on you. This was the first time it has locked up on me in my many years of using it, so it’s clearly a fairly isolated problem. In retrospect, the solution seems obvious, but, OMG, what a painful learning experience.)