Eric meant all the network hosts should have their default gateway set to point to the layer-3 switch.
The router is a different thing. The router needs a route which identifies your internal subnet, and sends traffic for that subnet to the Layer3 switch.
All this is very easy to understand and plan if you start with a diagram:
- draw a "cloud" representing each subnet you want to use: eg, 1 cloud for PCs, 1 cloud for servers, 1 cloud for voip handsets.
- Now you need to give each cloud a "router" so that devices within the subnet have a means to communicate with devices in different clouds. The hosts call this router their "default gateway". Each cloud for hosts should have ONE router. Ideally, all the clouds thus meet up on your Layer3 switch. Your Layer3 switch is therefore "connected" to all these subnets can can route between them.
- Now you need to worry about the routing you need between all your clouds and other places, eg, the Internet: eg, put a default route on the Layer3 switch pointing at your Netgear. For traffic to get back, you also need routes on your netgear pointing at the Layer3 switch for each of the subnets that exist on the Layer3 switch.
- The connection between the Netgear and the Layer3 switch is a "cloud"/subnet consisting of just two addresses: one on the Netgear and one on the Layer3 switch. This point-to-point subnet should not have any hosts in it.