How to? Expand or increase the ethernet ports?

[Mark_in_Hollywood]

What device can increase the number of ethernet ports on a network, which consists of this device as the modem:

AT&T Motorola NGV-510. Technically this is a wifi modem router combo. It has 1 WAN port and 4 LAN ports.

I have a Netgear WNDR3400v2 as an additional device. It has 1 WAN port and 4 LAN ports.

Lastly, does an "unmanaged ethernet switch" provide an additional set of LAN ports, by plugging an ethernet cable from one of the NGV-510's LAN ports to one of the switches LAN ports?

I hope I have asked this question in an intelligent way. I have no idea of what I'm doing and can best say I have 4 LAN ports and need one more LAN port and want the simplest solution I can find.

[Iowan]

My system has a cable modem connected to a router which has 4 ethernet ports. Into two of the ports are plugged cables which connect to switches.
There is a maximum of how many switches can be daisy-chained - I'd have to look up how many (I'm not near that, yet).
Does this help - or further muddy the water?