Nighthawk MK63S (MR60) Device Count Curiosity

Earlier last week I purchased a Netgear Skyhawk Mesh WiFi 6 system at Costco because I thought I could improve my network coverage, internet speed and stability.

Before I used an ASUS RT-ACRH17 router with my Arris SB8200 modem and despite the no reception spots I had a stable network, fairly fast internet speed and my tv's didn't have to buffer (wired and Wifi).

But now with the Mesh WiFi 6 system it seems that my network isn't quite as stable as is used to be. My tv is buffering all the time and the response time on my laptops and iPads is significantly higher than before.

The installation went pretty smooth and I have better WiFi coverage in my entire 3 stories home.

But the response time, to open a website, seems to be longer in comparison with my old router.

I bought the system because it claims to give me the best coverage and the fastest internet speed. Unfortunately this is not fully the case. 

Despite my COX mega fast internet 900 mbps download and 35 mbps upload, the network has difficulties gettting all the bits and bytes on my screens.

However the download speed in the speed test gives me 600+ mbps download and 33-35 mbps upload speed but it takes quite some time before the test is executed.

Any suggestion on how I can improve this?

Because I am seriously contemplating of returning this system to Costco due to its poor performance.

Thanks

Eric