We all have those tech problems that we kind of give up on. Like an annoying rattle in the car where you can’t track down the source, you just eventually acclimate to it until it feels like that’s just the way it’s always been. (Even then, you’ll find that every once in a while it will just bug you.)

But there’s nothing more satisfying than eventually discovering the cause of one of those issues and vanquishing it for good.

In recent months, I’d run into a weird situation. My M1 MacBook Air could access my iMac just fine via file sharing in the Finder: the iMac showed up in the sidebar, I could copy files back and forth, no problems. However, doing the opposite—accessing the MacBook Air’s files from the iMac—simply didn’t work at all.

It was quite the perplexing conundrum: I checked the file sharing setup in the MacBook Air’s System Preferences and everything looked fine. I attempted the tried-and-true troubleshooting step of turning sharing off and then turning it on again (even tried it with a reboot in between, just to make sure). No dice.

It seemed like the problem was further down, at the networking level. Attempts to use the Finder’s Connect to Server option simply timed out, eventually reporting that the server wasn’t available.…