I just got a used Macbook Air for a pretty good price, but it has problems with wifi. The previous owner said it would connect to some networks, but not others.
It connected to my phone hotspot just fine, so I figured the wifi-card isn't actually broken.
Here at home, I was unable to connect to my router. I tried using wireless diagnostics and one of the things it told me is that there was a conflicting country code. I gather that, for wifi, the Macbook gets its own country code from the first wireless network it sees. The first time I tried, the laptop had the country code 'JP', and was unable to connect. Then, I tried again, and it had the code 'GB', and was also unable to connect. The third time, I sat down next to my own router, and got the code 'NL' and I was able to connect just fine.
With my own Macbook Pro this has never been an issue and I have always been able to connect to every wifi network.
It seems like the country codes are the issue. Why is the Macbook Air unable to connect to wifi networks of a different country code? Is there something I can do about this, or will this be an issue forever?