Trouble with adding second subnet VLAN

Hi, I'm having a little bit of trouble getting my VLAN setup to work as i'd like on OpenWRT. i'm running the latest version on a Linksys WRT1200AC. My LAN is 192.168.100.*

I decided to put my VLAN with a new subnet on physical port 4 since i have nothing connected to it. My goal is to run untrusted IoT devices through this network so i can keep them off my main network.

The switch port list says the port #'s are reverse of what they're listed as on the device, so in order to assign the VLAN to physical port #4, I had to make a new VLAN for LAN1. So what I did is add a new vlan to the switch page on Luci, set eth1 to tagged and lan1 to untagged. It yelled at me that multiple vlans had lan1 on untagged, so i set it on the first row to "off" and saved it.

I then went to make a new interface which I set up by attaching the newly made vlan for the 4th port, and set it to have a static address of, and activated a dhcp server on it. I also set it to use google DNS (

I then made a new wireless network on my 2.4ghz band and attached this interface to it. As soon as I hit save, my LAN kept working but all WAN connectivity was lost, even on LAN and 5ghz band wifi. I could keep changing settings in Luci, but I could not get to any web sites.

I tried deleting the interface, the new VLAN, and set the switch back to the way it was before I started trying to make a new VLAN, but still couldn't get on, so after being sure the setting were what they used to be, i rebooted my router and now it works as expected again.

What did i do wrong trying to set that up? I looked at all the wiki pages but it's difficult for me to learn stuff that way, so i tried to watch a few youtube videos on it but none of the videos i saw were exactly the setup i am trying to make work.

In theory you are not wrong.
If you don't provide however the configuration files that you used, we cannot guess what is wrong. Although I tend to think you messed up the switch ports. Physical port #4 is switch port 0 according to the device page.


The switch page usually shows the connection status of each physical port. You can verify the logical-to-physical (labeled) mapping by connecting devices on each port (usually just port 1 and 4 are necessary, the others become pretty obvious).