Setup is:

A main router, then a second router which connects from its WAN port to a LAN port of the main router. This second router's goal is to establish a separated network for guest devices.

I disable the DHCP function of the second router, and set a static IP (which is different than the IP of the main router). For example if the main router is, then I would set second router to

If guests connect to the second router via LAN or WiFI, would the guest's devices be able to "interact" with the devices connected to the WIFI of the main router? Could there be any kind of interaction on Layer 2 or 3?

Is it correct to connect the WAN port of the second router to a LAN of the main router, or should it be LAN to LAN?

If this setup does not fulfill the "separation" criteria, what changes are needed to achieve separated networks (using a two routers approach - without the need of VLANs)?


Yes, you can do this and I do this. However, do not disable DHCP on the second router (different network).

Hook up the WAN port of the second router to a LAN port on the main router.

Give the WAN address a static IP on the main network.

Review the LAN network settings to make sure it is a different subnet than the main network. Leave DHCP enabled.

Since you made changes to the second router, restart it (not reset) and then test. Devices should have a different subnet than the main network, have Internet, but not see the main network.

This suffices for most people as they will use it as given. Dedicated hackers can probably get around this but I assume your guests are not dedicated hackers.

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    Here is a good article on VLANs (Layer 2) and Subnet isolation (Layer 3). Simple subneting works in my environment, but you can implement VLANs if you wish. cbtnuggets.com/blog/cbt-nuggets/… Now I have gone over and above for you and you might at least mark the answer as helpful. – John May 29 at 20:27

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