The gateway should be fine (http://www.netgear.com/service-providers/products/cable/gateways/cg3000-cg3100.aspx ) but I'm not there to try anything and I'm finding folk that don't want to become computer scientists.
Again, these products work in most instances but here is a system that doesn't work. What the issue is, is not evident given the facts so far. A better than average network savvy engineer would be needed. There are of course odd devices that can kill a WiFi network. Your post didn't reveal if this was a wired or WiFi connection. Yes we could clear that up but the bottom line is that it may be too painful to deal with.
Advice? Return products that can't find support. Go with stuff that works.
In the case of the smart TVs I've been known to turn off the smart part and add some Apple TV, Roku, Amazon Fire or other solution.
Ever since we changed to Optus Fetch TV, which brought with it a Netgear CG3000 Gateway, we have had intermittent complete loss of data. Any device connected to the gateway, wireless or cable, shows an active connection but no data comes through. Optus have been unable to locate the problem (4 visits, innumerable lengthy call to the help desk - all which shows there bing no problem). We now seem to have identified a pattern. Turning on the TV (a UA46ES7100) results in a cut off of all data. Turning it off fixes it. I have done it enough now for it not to be a coincidence.
Any and all suggestions welcome.