How to solve the issue that a Mac (Macbook Air) keeps on trying to use WEP to connect to Wifi? I have the latest version of Macbook Air with Mountain Lion, as of Oct 2013, and since one of the computers is an older one that needs WEP, the Linksys (Cisco) router is set to support both WEP and WPA.

However, with the Macbook Air, when the "cisco" is chosen from the list of Wifi connection, it keeps on saying, "Enter the password for WEP", and even if we enter the password, it won't connect.

What we have to do is, use "Join Other Network", and type in "cisco", and choose WPA or WPA2 Personal, and then type in the password, and it will connect, but the thing is, sometimes the network drops, or after the computer is rebooted, we will have to repeat the same steps again -- it won't remember the settings to auto connect (using WPA).

Is there a way to make this work more smoothly?
I set the Linksys (Cisco) router so that all the 2.4GHz and 5GHz support essentially the same thing: WPA Personal and it seems to work fine now.  

I think the issue was 2.4GHz and 5GHz was set to WEP and WPA, respectively, due to some 2.4GHz device using different security standard.  So I think the Mac might have some issue of not able to remember the connection, being confused by difference in settings of 2.4GHz and 5GHz.