Wi-Fi network could not be joined - Macbook Pro 2015
I tried several of the suggestions posted online and none of them worked for any more than a few minutes. I’ve owned this MacBook Pro for nearly 4 years and never experienced this problem until a few days ago. So I asked myself what had I changed in the last few days. I realized that I had recently purchased a USB hub, so I did some searching and found out that you can’t plug the USB hub into the rear USB-C connection on the left side of a MacBook Pro - exactly where I had plugged mine in. So I switched it to one of the right side connections and bingo - everything works great. This solution worked instantly without making any setup or network modifications. Could this be your issue?