Two routers on your network can cause headaches. For example, you can end up with local address problems. Among other things, the other router can misdirect addresses that the Netgear router usually handles, such as routerlogin.net or the usual IP address for a router, 192.168.1.1.
Unless you have specific reasons for using two routers – to create two separate networks for example – it is often easier to use just one router and then to set up the second router as a wifi access point. Netgear advises this, as does just about every site you will visit.
It may be possible to put the modem/router into modem only (bridge) mode and then to use the second device as the router. But some Internet service providers, such as BT in the UK, supply modem/routers that won't work in bridge mode. There may be ways to get the modem/router to cooperate, but sometimes it is easier to put the second router into AP mode. But that has its own drawbacks:
