A fixed IP address assigned via DHCP (also known as static IP mapping, or DHCP reservation) is a way to ensure that the client device will use the same IP address. This feature is especially useful when a client on the LAN needs to be reachable on a particular address, such as when forwarding a port to the device.
Fixed IP addresses allow you to control these IP address assignments using the DHCP server that is running on the UDM/USG. The advantage of this method is that the client configuration does not need to be altered and they can keep using DHCP instead of manually configuring a static IP address on the client. The fixed IP address is configured per network and must not overlap with other assigned addresses.
In this article, you'll learn how to assign a fixed IP address to clients using DHCP on the UDM and USG models on the latest firmware.
For more information on DHCP, see Intro to Networking - Dynamic Host Configuration Protocol (DHCP).
Assign a fixed IP address to a client device
Follow the steps below to assign the fixed IP address on the UDM/USG, depending on whether the client is known or not.
- Known client: a client that has previously connected to the network and is listed in the Insights > Client History section.
- Unknown client: a client that has never connected to the network.
1. Go to the Clients section and click on the client device to open its Properties panel.
2. Select the Configuration tab and expand the Network section.
3. Enable the Use fixed IP address toggle and enter the necessary information like in the example below and click Save.
IP Address: 192.168.1.100
3. The change will not be applied automatically as the client will still be using the previously assigned DHCP address. Optionally restart the client or renew the DHCP lease manually to force it to obtain the new IP address:
4. Clients that are assigned a fixed IP address will be displayed in the Insights > Client History > Fixed IP section.
1. Go to the Clients section and select the Add Client option.
2. Enter the necessary information. For example:
MAC Address: <client MAC address>
Alias: <client name>
User Group: Default
Fixed IP: Checked
IP Address: 192.168.1.100
3. Save the settings and apply them.
4. Connect the client device to the network.
5. Clients that are assigned a fixed IP address will be displayed in the Insights > Client History > Fixed IP section.
Assigning a Static or Fixed IP Address to a UniFi Device
Fixed IP addresses can be assigned to UniFi devices while they are still unknown (unadopted), and the process followed is the same as the one described in the Unknown Client Fixed IP steps from the section above.
Adopted UniFi devices can be configured with a static IP address (not relying on DHCP) by changing the network settings from DHCP to a statically assigned address:
1. Navigate to the Devices section and select the UniFi device.
2. Select the Config tab and expand the Network section.
3. Change the Configure IP option from Using DHCP to Static IP and enter the necessary information. For example:
IP Address: 192.168.1.5
Subnet Mask: 255.255.255.0
Preferred DNS: 192.168.1.1
Alternate DNS: Optional
DNS Suffix: Optional
4. Queue the changes.