Nighthawk r8000p not switching firmware when manually updated

A few weeks ago my parents got this Netgear Nighthawk router along with our new 300mbps connection from TDS telecom. We plugged it in and everything was mostly fine. Initially we only experienced slowness on the wifi signal, which I tried to remedy by factory resetting the router. This only worsened the problem.

I googled around to try and find a solution and one of the ones at the top told me to downgrade to an older firmware version. Which should have occured to me beforehand. Well, when doing this, I do exactly as stated. Upload the .chk file to the Netgear control panel and waited for it to boot up. I used the 1.1.4.6_1.1.85 firmware patch but as soon as it 'uploaded' it kicked me back to the main screen and in the top right corner it displayed the most current version still.

Auto-Update is off and we cannot return the router because my mother threw away the receipt. We payed almost 300$ for this and the constant disconnects on my wired ethernet connection is making me go insane. Can someone please help?