How to create 2 separate networks but still allow communication between networks

[Kosho123]

Hello,
I have a Router A (Asus RT-N66R) and Router B (Linksys WRT54G). The modem (Motorola SurfBoard SB6141) is connecting to Router A's WAN port. I want to create a separate network for smartphones or computers so if someone hacked into a computer or malware was spread, it would only effect that network and such things as NAS, printers, and smart home devices are on a separate network. The problem is I'm trying to make where a computer on one network can see the NAS on another network.


Could I connect a LAN port on Router A to Router B's WAN port to create separate networks but for Router A devices to still see Router B devices but not vice versa?

 

[RealBeast]

Connect the WAN port of B to an LAN port of A, give B a different network address, like if A is 192.168.0.1 make B 192.168.2.1 (any value for the third octet from 0 to 254 other than that used on A). Then on B use the address of A as the WAN and DNS address. Use different non-overlapping radio channels (selecting from 1, 6, and 11 for 2.4GHz), a different SSID and security passkey.

It will look like THIS and HERE is a little more detail on the setup to create a subnet with two routers.

 

[kanewolf]

Your RT-N66R router can create a guest wireless network that is separated from the rest of the network. The guest wireless only has internet access.