Model : Archer C5400

Hardware Version :

Firmware Version :

ISP : Cox Communications

When I first got the router, I configured the two 5Ghz channels for my wife and I, and the other for the kid. I noticed a while back that my channel was missing and my devices were all defaulting to the other two channels. Tonight, our electricity went out for about 10 seconds, and afterward the router just rebooted itself, repeatedly. I couldn't even log in to try to figure out the problem. I finally had to resort to a hard reset, and to reconfigure the network. When I first started setting it up, it offered me the three channels, plus three guest channels. But as I was finishing up, it only offered 1 of the 5Ghz channels and at the bottom of the screen, a message said, The 5Ghz network is unavailable due to restrictions in your region/country. What is the deal? Any ideas or solutions?

Thanks in advance, Chris