Nighthawk R7000 change bridge mode from 2.4ghz to 5ghz

I set my R7000 to bridge mode last year after getting a new Modem / router. The R7000 sits in the loungeroom with devices attached via ethernet. Wireless repeating is turned off. I really only want to use it wired.  
When I originally set it up which took me a long time to do I set it up on the 2.4ghz but I want to change that to 5ghz. (2.4ghz drops out all the time which is another issue of my main router.) The Status shows this 2.4ghz. By the way my main router is set up as 54Mps as it's the only way I can get it to work currently.
Is there a way of changing from 2.4 to 5 without resetting and starting again.