Ubiquiti UniFi USW Layer 3 discovery and adoption cheat sheet
Discover and adopt a UniFi USW switch when the UniFi Network application is on another subnet or site.
UniFi USW switches and UniFi Network. Layer 3 discovery means management adoption across routed networks; it does not require the switch itself to support Layer 3 routing.
Updated · Ubiquiti · 6 min read
| Step | What it does |
|---|---|
Identify the USW and its management network | Confirm switch identity, ownership and addressing |
Verify the UniFi Network application and site | Select the correct controller and inform address |
Test-NetConnection unifi.example.com -Port 8080 | Test the inform TCP port from an equivalent network |
ssh <device-user>@<switch-ip> | Connect to the USW management interface |
set-inform http://unifi.example.com:8080/inform | Point the switch at the UniFi Network application |
UniFi Network → Devices → Ready to Adopt → Adopt | Adopt and verify the intended switch |
DHCP Option 43 or DNS unifi | Review alternate discovery methods |
Compare routed adoption and Layer 3 switching | Distinguish controller discovery from packet routing |
Walkthrough
Use the correct UniFi site and an authorized administrator. Identify the switch management VLAN, IP address and current ownership before changing its inform target. A new or explicitly reset device can be adopted; do not factory-reset or take over an already managed production switch without an approved migration.
Step 1: Confirm switch identity, ownership and addressing
Identify the USW and its management network
Record model, MAC address, management IP, subnet, gateway and current adoption state. Check the DHCP lease or network inventory if the address is unknown. A switch already controlled by another application needs an approved migration, not an immediate reset.
Step 2: Select the correct controller and inform address
Verify the UniFi Network application and site
Confirm the intended UniFi Network application is running and that you are viewing the correct site. Identify its address reachable from the switch. For Official UniFi Hosting use the dashboard Copy Inform URL rather than guessing a hostname.
Step 3: Test the inform TCP port from an equivalent network
Test-NetConnection unifi.example.com -Port 8080
Run this PowerShell example from a Windows test host on the same management VLAN and with equivalent firewall policy as the switch; replace the hostname. TcpTestSucceeded confirms only that test host can reach TCP 8080, not that the switch can. Check routing, ACLs and return traffic for the actual switch.
Step 4: Connect to the USW management interface
ssh <device-user>@<switch-ip>
Replace both placeholders and use the authorized UniFi device SSH credentials. Device SSH credentials differ from UniFi Console SSH credentials. The initial SSH example applies to a factory-default device in Ubiquiti’s remote adoption workflow; follow your approved migration process for an existing managed switch.
Step 5: Point the switch at the UniFi Network application
set-inform http://unifi.example.com:8080/inform
Run this command in the USW SSH session, substituting the application IP or FQDN reachable from that switch. It changes the device inform target. For Official UniFi Hosting use its provided inform URL. Do not use the gateway IP unless it actually hosts or forwards the UniFi application.
Step 6: Adopt and verify the intended switch
UniFi Network → Devices → Ready to Adopt → Adopt
In the intended site, match the device MAC and choose Adopt. Ubiquiti notes that set-inform may need repeating after the device appears. Wait for provisioning and confirm the switch remains connected; an inform command alone does not complete adoption.
Step 7: Review alternate discovery methods
DHCP Option 43 or DNS unifi
For scaled deployments, Ubiquiti documents DHCP Option 43 and DNS resolution of unifi to the Network application. Check the options supplied on the switch management VLAN and the vendor-specific encoding. The device may try multiple inform sources, so remove unintended competing targets through an approved change.
Step 8: Distinguish controller discovery from packet routing
Compare routed adoption and Layer 3 switching
Discovery across subnets needs a reachable application and routed TCP 8080. Inter-VLAN routing on the switch is a separate feature available only on selected USW models; consult Ubiquiti’s Layer 3 routing guide if the switch should route client VLANs.
WORKED INCIDENT
Practical case: A branch switch does not appear in the central controller
Fictional teaching scenario; observations are examples, not captured production output.
Situation
A new factory-default USW has a management address on a branch VLAN. UniFi Network runs on a different subnet.
Investigation sequence
1. Confirm switch identity, ownership and addressing
Identify the USW and its management networkMatch the switch MAC to its management address and confirm that it is available for adoption.
2. Select the correct controller and inform address
Verify the UniFi Network application and siteIdentify the intended Network site and the application address reachable from the branch.
3. Test the inform TCP port from an equivalent network
Test-NetConnection unifi.example.com -Port 8080Test TCP 8080 from the switch management path or an equivalent authorized test host. In this example the equivalent test initially times out.
4. Connect to the USW management interface
ssh <device-user>@<switch-ip>After the network team corrects the approved route or firewall policy, connect to the switch with the authorized device SSH account.
5. Point the switch at the UniFi Network application
set-inform http://unifi.example.com:8080/informSet the correct inform URL on the USW and watch the intended application for its MAC address.
6. Adopt and verify the intended switch
UniFi Network → Devices → Ready to Adopt → AdoptAdopt the switch in the intended site and repeat set-inform only if the device appears but requires the documented retry.
Example findings
Illustrative findings: the switch has a valid management IP; the controller is on another subnet; TCP 8080 initially times out and succeeds after an approved firewall correction.
Interpret the findings
The timeout supports a connectivity investigation. A test from another host is supporting evidence, not proof of the switch path. Once connectivity works, check ownership, inform address and competing DHCP or DNS discovery settings if adoption still fails.
Verify the outcome
Confirm the correct MAC appears in the intended site, adoption and provisioning complete, and the switch remains connected. Verify management reachability and the expected port configuration after provisioning.
Escalation handoff
Provide switch MAC, model, management VLAN/IP, application FQDN, inform URL without credentials, TCP 8080 test source and timestamps to the network or UniFi administrator. Avoid factory reset until ownership and an approved recovery path are established.