C7000 Randomly drops internet, on my laptop with only a 2.4 ghz connection.

I have a contract with Netgear for support, and I use to own a C3700, but the range was poor (it would not reach my bedroom) 35 feet away.  So I upgraded and purchased a new C7000.  The range is good and I can broadcast HD TV through my Roku no problem now.  However, I try and search for stuff on the internet with my laptop (which can only connect using the 2.4 ghz broadcast, and every once in a while (randomly - maybe once every other day) as I am searching.... the browser will just time out and come up on the screen with the message "NO INTERNET CONNECTION".   

If I look in the bottom right corner on the computer, the image of the "fan" icon for internet connection indicates it does not have connections to my WiFi 2.4 ghz broadcasted network.  I click on the "fan" and I see my broadcasting SSID but if I click on it - it also times out and comes back with "Can not connect".  So if I go into WiFi settings I search for available broadcasts to connect to and it does not show my broadcasted SSID - if fact when I first go to the available list it does show my SSID but as it is searching for available networks it disappears!!!!!   WHY WHY WHY ?....

All my other devices, Roku, Cell Phone, Tmobile Cell Tower, Surface, another laptop all are still connected and working fine!!!!!  Both on 2.4 ghz and 5.0 ghz bands. 

Note - If I reboot my laptop - I get reconnected and it works for a while (maybe 1 or 2 hours) then the same issue happens again!  Help!  I have called Netgear four or five times for this issue and every time they go through the same processes.  By asking me to go into the wireless settings... 1. Go to 192.168.0.1  

2. Login as the admin and use password  

3. On the Basic tab click on Wireless

4. They ask what Channel are you on for the 2.4 ghz - 

           Please change it - (and normally) they say 01, or 06, sometimes 11 

5. They ask what is the "mode" (speed of connection) - normally it is set to "Up to 600 mbps"

           Please change it to either "Up to 289 mbps" or "Up to 54 mbps" 

6. Same steps for the 5.0 ghz settings which has no problem but we go through this process anyway ....

7. Click on "apply" 

8. Open up browsers - see how they work - go to Speedtest.net - check speeds 

             Note when I have internet connection it is fine no issues 

           I explain this point but the techs continue to make changes - 

9.  Go to the Advance tab 

10. Click on "Advance Setup" 

11. Click on "Wireless Settings"

12. What does it say for the " Fragmentation Length (256-2346):"? 

         We typically change this by one digit or two digits say 2306 or 2303  

13. What does it say for the "Preamble Mode"? 

         We typically change this also by one digit or two so if the above is set to 2306 we use 1+ so it would be 2307 

14. Click on Apply 

15. Go to websites check speeds etc.... Same damn thing and after a few hours or few days - same freaking issue 

ANY HELP WOULD BE GREATLY APPRECIATED - mikeruth12@yahoo.com