Hi all. I had exactly the same issues as soon as I got my MacBook air. I try to connect to my school Wi-Fi - I spent 1 hour on the phone with Apple Care. I was instructed if I spent $99.99 that "THEY" will try to help me out to set the the Wifi.
It did not sit well with me. I am not a computer Guru but I have been setting up my own network for years.
I told them, all other devices can get on the internet but this new 2013 MBA.
Obviously, it did not go anywhere and I refused to pay the $99.99.
I came home and found I had very little trouble to get on my own network.
Since I have a few wireless router/AP floating around (they were not in used at all), so I tried to figure out what might be the issues.
First - the security - I found the WPA2 (personal) with AES will work.
BUT NOT WPA-TKIP (that was the set up in my school)
I also tried the auto channel or any fixed channel (did not make any difference as long as it is WPA2-AES)
I used D-link (N standard) and Netgear (N standard) - both demonstrated the same success.
of course, they were set up as DHCP. I had no luck if I assigned the MAC address filter.
what I did was - I reset all the router, started from the scratch and I had no issues.
I brought my own router next day and placed in my office. Every machine was happy, even I did not broadcast the SSID (mainly for security). All the machines run like a charm.
Have not tried on G standard yet.
will bring my laptop to different places to see if any issue might occur.
Sam