I installed a new wifi router and airport will not connect automatically to it. It sees the network but will not connect unless I tell it to.

Question

I installed a new wifi router and airport will not connect automatically to it. It sees the network but will not connect unless I tell it to. I can't find anywhere in the utility or network preferences that will allow me to choose this router as the default. How do I fix this? BTW I'm using Lion.

Answer 1

Are there any previous networks that you have used that have the same password as Molly?  YES
Using System Preferences > Network > AirPort Advanced again, you need to remove any listings of previous networks that used the same password as Molly. Click the name of the network and click the - (minus) button at the bottom of the list of connections.
Also delete any other networks (except Molly at the top of the list) that might have used the same name...Molly in the past.
Delete any other networks that you no longer need so that your Mac will search for networks more quickly
Click OK, then click Apply
Open KeyChain Access and look for a listing of any old networks that you no longer need. Click to highlight the name of the network, then click the Delete Key on your computer.
Then look for any old networks that might have used the name Molly in the past and do the same for them.
Then look for any old networks that might have used the same password as the password for your "new" Molly network and delete them in the same way
Click the KeyChain Access menu just next to the Apple icon in the upper left corner of the computer screen
and then click KeyChain First Aid
Enter the main administrator password for the Mac you are using and highlight the Repair button. Then click Start. You will see a message that repairs have been completed
Quit Keychain Access
Power down the entire network...all devices...order is not important
Power up the modem first, then your main router, the other devices one at a time
Log on to Molly and see if the Mac remembers it after a few tries. If not, I'm afraid that you will need to change the name of the wireless network and password on your router due to corruption issues on the Mac. You have done everything possible without re-installing the complete operating system.