Nighthawk Router Extra Connection Appearing (sometimes)

Typically my Nighthawk router works amazing, but sometimes an additional wifi channel is opening up. My typically "Netgear29" will sometimes also be accompanied with a "Netgear29-5G2". This new network also runs at substantially higher speeds usually, and doesn't recquire a password. They are both 5G. I know it has the tri-band, but I have it set up to automatically distribute the devices. Why would my second 5g band suddenly be popping in and out of existence like that? And... Not automatically just connecting stuff to it?