the problem is that as soon as I hook up the netgear, seemingly no matter how I try to configure it, it knocks the rest of my network offline.
A bit more information would help. For example, what do you mean by "knocks the rest of my network offline"? does that mean you don't get any response to a ping directed at www.google.com from the pfSense console? Does it mean you can't access the pfSense web GUI? etc etc. Details like When I do … on a system connected to ... I get response ... when I expected to see ... would be much more informative than the executive summary.
Perhaps you have duplicate IP addresses, perhaps you have multiple WiFi access points using the same WiFi channel, perhaps you had a panic when some part of the network didn't behave as expected and you overstated the problem.