Both LAN and WAN computers won't stay connected to internet

[Lovenharmony]

I’ve been having an issue for the past 3 weeks keeping my primary wired PC and the wireless PCs in my home network connected to the Internet. The internet constantly disconnects intermittently (with no rhyme or reason)
and have tried everything I could do to try to resolve the issue. I connected my wired PC directly to the Optimum Online Cable Modem (Arris Telephony Modem v 3.0) I use to connect to the internet and it still has connection
issues.

Most of the time when it drops the connection, the network icon on the taskbar says I’m still connected to the internet. Only after a few minutes will the network icon finally appear with the yellow exclamation point over it. When I right click the network icon, I will check the network and sharing center and will click on the red x over the connection from my router to the internet. Sometimes when Windows checks for internet connection problems, it will state that it can’t resolve the issue, and other times it will state that the DNS server isn’t responding or cannot communicate with Primary DNS Server.

I’ve had my ISP cable guys check my cable wire (coaxial cable wire) for packet loss, swapped my old router for a new one (twice), readjust the connection outside for a specific low node issue, and did 3 or 4 trace routes,
conducted a multitude of ping tests, went on speedtest.com to check the signal strength and they state that everything looks great on their end. I also used different Ethernet ports built into the motherboard of my PC to see if my network adapter was the issue, but my internet connection it still continues to drop, even when only my pc is wired directly into the cable modem. I even changed the Ethernet cables themselves to see if they might have been faulty, but it still continues to drop.

I forgot to mention that I did the flushdns and registerdns commands , plus reset the TCP/IP, but my internet connection still continues to drop. The only thing(s) I have not done is change the network adapter completely (install a new Network PCI adapter ) and have the cable guy re install an entire new coaxial cable wire, of which my ISP is adamant that I don’t need to have done since when I am able to connect to the internet, my signal strengths
and speeds are great (download speeds of 32mbps and upload speeds of 5mbps).

I know I’ve said a mouthful, but I’m at a loss of what I should do next. When connected to my cable modem through my wireless N router, ALL of my PCs (my wired PC and my wirelessly connected PCs through my home network)
will disconnect from the internet . Both the cable modem and the wireless N router still appear to be online (none of the lights on the front of the modem or router have changed ) I’ve even considered the strength of the ethernet cable itself, possibly thinking that the ones I have may not be strong enough for my internet speeds (purchased a CAT 6 Networking Ethernet Cable). My router , OS, cable modem, ISP, motherboard, and built in network adapter specs are shown below;

ISP: Optimum Online (with Boost Service)
OS: Windows 7 Ultimate (with latest Windows 7 Service Pack 1 updates)
Cable Modem : ARRIS Touchstone DOCSIS 3.0 E-MTA Telephony Modem TM802
Wireless Router: Netgear Rangemax Dual Band Wireless N Gigabit Router WNDR3700
Motherboard: ASUS Rampage Formula
Built In Network Adapter: Dual Gigabit LAN (2 RJ45 Ports)

Any help as to what might be causing the problem will be greatly appreciated. Thanks in advance!

[Edbert]

Well according to me the primary suggestion from my side is to keep the simple test. All that the various ports / cables / etc did nothing to isolate the problem. You start by making sure you have a clean machine free of spyware / malware / virus' s. Try this machine at a friends house without internet problems whatsoever. Then, kick back with a direct connection to the modem - router is removed from the mixture. Then work with your ISP to find out why you'll fall. A single PC connected directly to the modem should not lose the network connection.