--- title: "Configure DHCP Option 43 for UniFi devices to enable remote adoption across subnets" description: "Configure DHCP Option 43 so UniFi APs and switches auto-adopt across subnets. Includes the hex converter, OPNsense + Mikrotik examples, and a UDM guide." date: 2024-06-26T10:50:17+00:00 modified: 2026-06-05T18:53:38+00:00 author: James Kilby categories: - Homelab - Networking - VMware - vSphere - Hosting - Ansible - Automation - Docker - Traefik - VCF - Veeam - Nutanix tags: - #DHCP - #Option 43 - #Unifi url: https://jameskilby.co.uk/2024/06/unifi-dhcp-option-43/ image: https://jameskilby.co.uk/wp-content/uploads/2024/06/Ubiquiti_Networks-Logo.wine_-1024x683.png --- ![](https://jameskilby.co.uk/wp-content/uploads/2024/06/Ubiquiti_Networks-Logo.wine_.png) [Homelab](https://jameskilby.co.uk/category/homelab/) | [Networking](https://jameskilby.co.uk/category/networking/) # Configure DHCP Option 43 for UniFi devices to enable remote adoption across subnets By[James](https://jameskilby.co.uk) June 26, 2024 · Updated June 5, 2026 • 📖2 min read(302 words) 📅**Published:** June 26, 2024•**Updated:** June 05, 2026 ## Table of Contents ## Intro This guide shows how to configure DHCP Option 43 so UniFi devices can be adopted remotely across subnets. I have recently juggled some of my homelab services around, which involved moving my UniFi server to a different subnet. This meant that new UniFi devices could not find the UniFi server for adoption/control purposes as this is usually done with broadcast. This was part of my wider [home network upgrade](https://jameskilby.co.uk/2024/09/home-network-upgrade/). ## Layer 3 Adoption Options For Remote Adoption/Layer 3 UniFi supports: * SSH * DNS * DHCP Option 43 I discounted SSH as who wants to manually log into things and make changes and I discounted DNS. That left me with DHCP Option 43. ## Configuring DHCP Option 43 I decided to configure my DHCP server to hand out “option 43” on the network subnet the Access Points were connected to. The implementation of this will differ depending on what DHCP server you are using. Mine is the one built into my WatchGuard Firebox M200. In this, I have set a custom option and then it asks for four values: Code| 43 ---|--- Name | Unifi Type | Hexadecimal Value | 01:04:c0:a8:14:02 All of which are straightforward except the last one so let me explain. It is made up of 2 parts… The first two parts 01:04 is fixed for UniFi. I am hosting the controller on IP 192.168.20.2 The remaining part of the value (c0:a8:14:02) is the IP address of the UniFi controller in Hex. Please note this method does not support DNS. A multitude of tools exist for converting IP to HEX one can be found [here](https://www.browserling.com/tools/ip-to-hex) And there you have it. I can connect a factory fresh UniFi device to my network. DHCP will hand out an IP on one subnet and tell the device how to reach the controller in a different subnet. ## 📚 Related Posts * [MikroTik CRS504 Review: 100Gb/s Networking in My Homelab](https://jameskilby.co.uk/2022/12/100gb-s-in-my-homelab-sort-of/) * [Homelab Network Upgrade: DACs, 40Gb/s vMotion & pfSense](https://jameskilby.co.uk/2022/01/lab-update-part-3-network/) * [Automated VCF 9 Offline Depot](https://jameskilby.co.uk/2026/04/automated-vcf-9-offline-depot/) ## Similar Posts * [ ![Forcing an Upgrade to vSphere 8](https://jameskilby.co.uk/wp-content/uploads/2022/12/Screenshot-2022-12-14-at-21.45.23.png) ](https://jameskilby.co.uk/2022/12/forcing-an-upgrade-to-vsphere-8/) [Homelab](https://jameskilby.co.uk/category/homelab/) | [VMware](https://jameskilby.co.uk/category/vmware/) | [vSphere](https://jameskilby.co.uk/category/vsphere/) ### [Forcing an Upgrade to vSphere 8](https://jameskilby.co.uk/2022/12/forcing-an-upgrade-to-vsphere-8/) By[James](https://jameskilby.co.uk) December 14, 2022 · Updated June 1, 2026 I run a reasonably extensive homelab that is of course built around the VMware ecosystem. * [ ![Starlink Satellite Internet Review: Rural Broadband Solution](https://jameskilby.co.uk/wp-content/uploads/2022/10/spacexs-starlink-to-supply-free-satellite-internet-to-famili_u44u.1920-768x432.jpg) ](https://jameskilby.co.uk/2022/10/starlink/) [Homelab](https://jameskilby.co.uk/category/homelab/) | [Hosting](https://jameskilby.co.uk/category/hosting/) ### [Starlink Satellite Internet Review: Rural Broadband Solution](https://jameskilby.co.uk/2022/10/starlink/) By[James](https://jameskilby.co.uk) October 11, 2022 · Updated June 1, 2026 Since moving to Dorset last year internet connectivity has been the bane of my existence. 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