OPNsense Forum

English Forums => Virtual private networks => Topic started by: malebron on October 28, 2026, 09:09:40 PM

Title: Creating VLANs with Dnsmasq DHCP
Post by: malebron on October 28, 2026, 09:09:40 PM
Using OPNsense 26.7.7 on bare metal with a Unify managed switch (USW Pro SG8) and several Unify APs. My very basic flat network has worked well for years.

I finally decided to add VLANs for Guest and IOT. Before starting I upgraded everything to the most recent releases, including migrating from ISC DHCP to Dnsmasq DHCP as recommended. Everything went smoothly.

I followed the steps in several videos as carefully as possible, but they were based on older software versions with different UIs.

Everything looks right as far as I can tell, but when I try to connect via WiFi to the IOT SSID connection fails with "cannot get IP address". I assume the problem is in the DHCP setup somewhere, but I can't find it. (Everything else is working as before)

Observations
In the videos using ISC DHCP there is a simple checkbox to activate DHCP for each VLAN. I can't find anything equivalent for Dnsmasq. It seems you just set the range and enable for all interfaces under Dnsmasq-General.

One video showed the VLANs listed under Interfaces on the dashboard. I only see the physical interfaces listed (LAN and WAN).

Any help in troubleshooting this would be appreciated. It's very basic setup so I'm probably missing something obvious.

Thank you!
Title: Re: Creating VLANs with Dnsmasq DHCP
Post by: nero355 on October 28, 2026, 09:27:04 PM
Sounds like you have not created any VLAN Interfaces and assigned them to one of your unused NICs ?

Please post what you have done so far step-by-step and what is working or not exactly ;)
Title: Re: Creating VLANs with Dnsmasq DHCP
Post by: malebron on October 28, 2026, 09:58:27 PM
Thanks nero355

VLANs are assigned to my LAN port (10Gb) which is uplinked to my switch.

They show listed under the interfaces tab and under Interfaces: Devices: VLAN

Correct DHCP ranges are shown on interfaces: Assignments

Under Services: Dndmasq DNS and DHCP: General the VLANS are listed under Devices ("All" is selected)

QUESTION:
For a VLAN tag 20 with range X.X.20.2-X.X.20.254 I'm assuming the DHCP server IP I specify on the switch is X.X.20.1  ?

Thx

Title: Re: Creating VLANs with Dnsmasq DHCP
Post by: nero355 on October 28, 2026, 10:06:37 PM
Quote from: malebron on Today at 09:58:27 PMVLANs are assigned to my LAN port (10Gb) which is uplinked to my switch.
- Is the Port on the Switch configured as TAGGED ?
- How did you configure the Port where the Accesspoint is connected ?
- How did you configure the Accesspoint ?
- Do you have more than 1 Switch ?
- Did you copy the Default Allow Any to Any Firewall Rule from the Default LAN network to the VLAN Interface network ?

QuoteFor a VLAN tag 20 with range X.X.20.2-X.X.20.254 I'm assuming the DHCP server IP I specify on the switch is X.X.20.1  ?
That is one of the correct options and in this case the most used one :)

But I assume you don't do it on the Switch and configure on your OPNsense instead ?!
Title: Re: Creating VLANs with Dnsmasq DHCP
Post by: malebron on October 28, 2026, 10:46:38 PM
Urgh. I should watch more episodes of the IT Crowd ("Turn it off and on again")!

I simply rebooted OPNsense (suggestion from AI) and my VLANs now show up on the dashboard and I can connect to my IOT network via WiFi (although without internet). I can see that it assigned an IP address in the correct range.

I configured the firewall rules to be wide open for testing, so I don't understand why it can't see the internet. More troubleshooting...

Thanks for taking the time to help.