Right - I don't intend to advise you at this stage, as I don't really feel in a position to, but I can explain a bit about the hardware. That might help you.
What we lazily call a router can contain up to four different things, which are also available as separate items. The one-box products are just that, convenient for some people, like most domestic setups, but not necessarily having the same level of "excellence" in each component.
The four items are a modem, linking into a router, then hanging off the router is an ethernet switch and possibly a Wireless Access Point.
Think of your computer. Processor, RAM, disc, ethernet port, wireless point, amongst other things. The ideal configuration for one person can be different from another's. I look for small disc, medium processor, biggest RAM I can get, and wireless "n", as the best combination for my requirements within my budget.
Your router has three of the four. No modem. Your maximum input from the net (at the moment) is 80Mbps, which should get out of the Openreach modem into any router and out the other side into the built-in switch with no trouble. I believe that switch should also cope with sending that out of any one of its four ports. More techie people may contradict me there, as my belief could be wrong. But not dramatically so.
Your main reason for wanting a gig switch is for internal traffic on your LAN. By getting a gig switch, they look to be cheap, and connecting that to one of the Netgear ports, then everything else to the gig switch, job done! Cheap and easy if it proves satisfactory, and only £20'ish gone if you can't resell it. (At that price I don't think there would be much resale market, but I don't know).
As I said, I might get shot down on this, but if I do, so be it
. Or maybe people will agree that it fits your particular needs. I'm just throwing it in as what I woudl be inclined to do. A dedicated switch getting on with running the LAN.
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