How to Configure Unifi UDM PRO DHCP Relay To Use Windows Server DHCP
In this tutorial you will learn How to Configure Unifi UDM PRO DHCP Relay To Use Windows Server DHCP. This will come handy when you want your Windows Server to be the DHCP provider. This tutorial is based on Unifi Controller version 6.5.55.
Let’s get started.
First make sure you are running the latest controller version. At the time of this publication, it is 6.5.55. I will be progressing through this tutorial under the impression you already have a Windows DHCP Server already running. If that is not configured click: How To Install And Configure Windows DHCP Server.
1. Log into your UDM Pro using unifi.ui.com or its IP address.
2. Access the Unifi Controller and click Settings 
3. Click on Networks. Now you should be presented with all your current networks maybe even just the Default LAN if your UDM Pro is coming right out of the box
4. Edit your default or primary LAN and give it a name. Afterwards locate and click on the Advanced dropdown. 
5. Provide your network domain name. In my case its HDN.local which is short for Home Domain Network, if anyone was wondering. 
6. This is important to NOTE, before you even move forward with this you will need to make sure that your UDM Pro has the correct default gateway you want it to have. So, apply that first. Now that you did your due diligence, we can now select DHCP Relay for your Primary Lan.
7. Afterwards click Apply Changes.
8. Now let’s click on Advanced Features. 
9. Scroll to the bottom and click on Advanced Gateway Settings.
10. Locate and click on DHCP.
11. Now that you’re in the DHCP utility click the dropdown for DHCP Relay.
12. Type in the IP address of your DHCP server and click Add.
Reboot some of your network equipment and you should now see devices obtaining an address lease from your Windows DHCP Server.
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Hi, I am new to UniFi products and just have gotten a UDM-Pro and USW-Pro. I have set a vLan which uses the DHCP Relay for my server. This works fine. However, I would like to be able to use the UDM-Pro as a gateway to able able to use the WAN Failover since I have 2 internet service providers. How do I go about setting this up since the main UniFi Lan is on a different subnet from my server lan. I tried setting up the gateway/subnet but my network does not see the device and I cannot connect to it.
Hello JJ,
Thank you for the visit! The UDM Pro fails over automaticly to wan2 regardless of whatever vlan anything is on, you just need to configure wan2 with the correct addresses or use DHCP to obtain and address automatically.
I am just guessing here but I am hoping that your current network config starts with your Modems connected to your UDM PRO then connected to the switch and your server is connected to your switch? If your vlan is configured on your UDMPRO you need to set that vlan gateway of the udmpro on the Windows Server DHCP. However I may need more information to understand more clearly what your trying to accomplish. I have a discord channel that you can contact me on to disscus further.
Hi, Yes Maybe I could have the discord channel?
My vLan 2 on the UDPRO is configured as DHCP Relay, which has a different subnet than the main LAN of the UDMPRO.
What other information would you need?
Hello, I have follow your settings but my WiFi antennas refused to send dynamic IP’s from my DHCP server.
I have the latest UDM Controller Version 7.2.94 and all my UAP-AC-M have the latest update 6.2.41.
In the UDM controller make sure the vlan’s are created and assigned to the SSID. Make sure the switch port has the vlans enabled as well. It is usually a simple oversight.
Patrick,
Thank you for the walk through. I have attempted this to use pfSense as the DHCP server for my VLAN. I looked a the network version of my UDM Pro and it shows Network 7.3.80. Is that the same as your OS reference? A few questions:
1. I assume that the screenshots are for that older version. What I see is under Networks there is a place to add my VLAN network and then set the UDMPro as the device then I am able to set it as DHCP Relay. I put in the IP / subnet for my pfSense VLAN and save. I then assigned one of the UDM ports to the new network to get the assignment. Did not work…no assignment. I reverted back to the default lan on the UDM to make sure the device was working and getting a dynamic lease on an IP. That was good.
2. This leads me to believe that there is an issue with the UDM Firewall. I tried adding LAN IN, LAN OUT and LAN LOCAL rules to include the VLAN GW and still nothing allowing a lease assignment for the VLAN to the device.
Thoughts?
The tutorial is for version 6 of the unifi controller however the concept is still the same.
Are you adding the network on the udmpro to the same vlan that the pfsense is providing dhcp from?
Hi,
I have problem with DHCP server mode.
I need to replace an existing dhcp service that only supports a pool of 255 addresses. I have over 1000 clients and several access points. After enabling the dhcp server mode on the AP, there is a conflict in the network. How to do it? Does Access Point U6-Lite have the ability to configure NAT with its own DHCP server?
Hello Krzysztof
You should assign static IP addresses to the AP’s outside of a DHCP pool so no conflicts are to occur. If you I understand correctly you need to increase DHCP Range on the DHCP Server. I have subnet calculator https://patrickdomingues.com/simple-subnet-calculator/ that can help with that.