I completely understand the frustration of having an inconsistent internet signal especially when it goes unresolved for months. I have checked your network and there are no outstanding issues in your area. Are there any splitters or amplifiers that are connected to the coaxial that is screwed into the back of your modem?
Sorry for the late reply. After numerous phone calls to Netgear pleading to update the firmware we had no other choice but to go with Panoramic Wi-Fi. Our problems went away instantly when we installed the new device. The downside is that now I have to pay a monthly rental and I own a $200 brick. Also, port forwarding doesn't work on the Panoramic Wi-Fi.