Automatic Mesh + Separate WLANs (Public / Internal / Mesh) with OpenWrt (Archer C7, Shared Subnet)

Hi everyone,

I’d like to share my planned setup and ask if anyone here has already implemented something similar or has experience with related concepts (e.g. Freifunk, batman-adv, 802.11s).


Goal

I am running several 19" boxes with OpenWrt routers (Archer C7).
The idea is that each box can operate standalone, but as soon as multiple units are active, they should automatically form a mesh – no master/slave roles, all nodes equal.

Each box should broadcast three different WLANs:

  1. Device WLAN (public / for clients / end devices)

    • 2.4 GHz + 5 GHz, same SSID name (e.g. “Mixer01” or “Controller01”)

    • This WLAN should only have access to a specific port on the router (Port 1, where e.g. a mixing console is connected)

    • No access to the rest of the network or mesh

  2. Mesh WLAN

    • Separate SSID (e.g. “MeshNet”)

    • Based on 802.11s + batman-adv

    • Provides the interconnection between the boxes

    • Works automatically, no need to decide who is master

  3. Internal Staff WLAN

    • Separate SSID (e.g. “InternNet”)

    • SSID hidden

    • Full access to the entire mesh/LAN

    • Intended for staff/technicians who need full access to all devices


Addressing and DHCP Concept

  • All boxes run in one large subnet (e.g. 10.0.8.0/21 with netmask 255.255.250.0).

  • Each box runs its own DHCP server, but only hands out addresses from a defined range.

  • Example:

    • Box 1 → DHCP range 10.0.10.0–255

    • Box 2 → DHCP range 10.0.11.0–255

    • Box 3 → DHCP range 10.0.12.0–255

    • Box 4 → DHCP range 10.0.13.0–255

    • Box 5 → DHCP range 10.0.14.0–255

  • Advantages:

    • All devices remain in the same subnet, so they can communicate directly without routing.

    • No DHCP collisions, as each router only serves its own range.

    • Standalone operation works as well, since each box always controls its own pool.

Additionally:

  • Devices permanently connected to Port 1 (e.g. controllers, web servers, mixers) will have static IP addresses.

  • This ensures these systems are always reachable at the same IP, regardless of whether the box is running standalone or in a mesh.

  • Mobile devices (phones, laptops, etc.) will not be connected via Port 1 – they only use the public device WLAN.


Planned Technical Setup

  • VLAN separation:

    • Port 1 = VLAN for the public/device WLAN (with fixed devices and static IPs)

    • Ports 2–4 + Mesh = VLAN for the internal LAN

  • batman-adv:

    • Automatically distributes connectivity across all mesh participants

    • No central role, self-healing

  • Firewall:

    • Device WLAN is only allowed to access the VLAN of Port 1

    • Internal WLAN is allowed full mesh access


Questions to the Community

  • Has anyone here implemented a similar setup already?

  • Are there known pitfalls when combining 802.11s + batman-adv + multiple DHCP servers in a /21 subnet?

  • Freifunk uses a very similar approach – any feedback on stability with Archer C7 and OpenWrt, especially with 5 devices meshed together?

  • For static IPs on the Port-1 devices: is it better to assign them directly on the device itself, or via DHCP reservations?

Thanks a lot for your input and experiences!

There are five ports on each device.
How many chatbot coins you spent to call 30-some years old DHCP standard a freshly invented concept?