AC1600 Unable to update firmware (Not Tab saying Upadate)

I have a Netgear Wi-Fi Router AC1600, C6250 v1,  I’m presently on Cox.net and all works correctly and able to access the internet with my direct wired desk PC as well as my Wi-Fi devices.

 

My Netgear firmware presently 1.01.24 and see that there is an upgrade version of firmware to 1.0.4.26

So I downloaded it and unzipped and ready backed up all my settings etc.

 

I login to my router using my Desktop PC. (Win7 Ultimate)

 

I go to the Advance Tab I open Admin. Tab and I do not see any selection that says Update Firmware nor Check Updates….

I have tried other computers as well as the Nighthawk App and all do not show anything that will allow me to update my firmware.

 I also did a full factory reset of the router.

Could Cox have done something to stop me from seeing the tab and I only get updates when Cox say OK? 

 

Hopefully this gives you a clear picture to my question.

What can be wrong and how can update my Netgear firmware?