Need help with allowing and dissallowing on router.

I have a printer that is wireless and the tv that connects wirelessly (DISH).  I have 2 computers that are hard wired.

Looking in the settings I can see that I can disable the 2.5 and 5 GHz channels (wireless) separately.  My printer is on the 2.5 and the tv is on the 5.   Why does it kick one computer on ethernet off if I uncheck the enabled on the 5 GHz .  Is it crosswired or something?

Val