My wireless network suddenly not providing IP addresses while my sister networks and 5GHZ networks are.

So I have a network setup on my airport. I have 2 Android phones, 4 windows-7 systems and 3 Mac systems. Suddenly yesterday morning internet connections on everything went down. Luckily my phone told me it couldnt obtain an IP address. I tried connecting to my guest network and it was fine. I also tried connecting to my 5GHZ network an it too was fine. If I try to connect to my main network it doesn't connect. Do networks go bad or become corrupted? I assume I need to start a new network but is there something I did wrong? I do run multiple VPNs not simultaneously at certain points throughout the day. I only say this because my Airport Extreme goes a little crazy and I have to reset it when I do run a VPN. I also have an Airport Extreme connected within