R6220 not connecting to the internet on 2.4ghz

My R6220 is about 6 months old. It transmits on both channels but only the 5ghz will connect to the internet.  Ethernet connections work as well.  I've tried factory reset, changing channels, etc. Any ideas? Since it's out of the 90-day help period Netgear basically wants to sell me a new warranty to troubleshoot it!