On UniFi gateways such as the Dream Machine or Cloud Gateway, the LED tells you first whether the gateway has lost its internet link. Ubiquiti's LED article says a UDM with a blue LED that flashes off every five seconds has no internet connection, a steady blue LED means the device is adopted and running normally, a steady white LED means it is ready for adoption, and a UDM flashes only white during an upgrade. If the device does not turn on, Ubiquiti's offline article gives the physical checks in order:
The checks in more detail
look for any sign of power, replace the cable because damaged cables are one of the most common causes of power and link faults, try a different switch port or PoE adapter to rule out port damage, and if the unit is still in warranty request a replacement through the RMA portal. For a gateway that is on but reports no internet, work through the connectivity article: check the WAN cable and the modem or ONT, power cycle the modem for a few minutes, confirm the WAN port receives an address in the gateway's Internet settings and look at whether the address is a private range, which would mean another router or carrier NAT sits in front.
If the device and the application cannot reach each other on TCP port 8080, adoption and management fail even though clients still browse. A gateway that had internet and lost it after an update should be checked for reachable DNS servers and for UDP ports 53 and 123, which updates need. If nothing works, test the modem with a laptop plugged straight in, and call the provider if that also fails. Reset last, using the Reset button or the app. A useful habit is to check the gateway from two places: from the Network application on the LAN and from the mobile app on cellular data.
If the app shows the gateway online but clients have no internet, the fault is between the gateway and the provider; if the gateway is unreachable from outside too, the console or its uplink is down. Write down the WAN address, gateway address and DNS values the gateway reports before you call the provider, and note whether a second WAN is configured for failover, because a failover setup can mask a fault on the primary link until both fail. If the gateway shows a WAN address but names do not resolve, that is DNS, not the line, and the fix is different, so test by pinging a public address and then a name before you decide which it is.
Differential
Likely causes of “Ubiquiti UniFi gateways has Wi-Fi but no internet”, and how to tell them apart
- 1
A modem or ONT that needs a restart
What separates it The blue light flashes off every five seconds because the modem or ONT has stopped responding
How to confirm Power cycle the modem or ONT for a few minutes, then let it come back before you test
- 2
A bad WAN cable
What separates it There is no link on the WAN port because the cable is bad
How to confirm Replace the cable, and try another port, then check that the port light shows a link
- 3
A provider outage
What separates it A laptop also fails when connected straight to the modem because the provider has an outage
How to confirm Call the provider, since the fault lies outside your home and outside the gateway
- 4
A private WAN address
What separates it The gateway has a private WAN address, which points to a double NAT or carrier NAT
How to confirm Bridge the upstream device, so that the gateway gets a public address from the provider
- 5
Blocked DNS or update ports
What separates it Updates and name lookups fail because the DNS or update ports are blocked
How to confirm Allow DNS, and UDP ports 53 and 123, through any firewall between the gateway and the internet
Before you touch a setting
Record this first — changing settings destroys the evidence
- The LED state and any screen message
- The WAN address in Internet settings
- What the lights on the modem or ONT are showing
- Whether a laptop works on the modem
Try in this order
0 of 7 completedRead the LED
ReversibleRead the light on the gateway, since a blue light that flashes off every five seconds means no internet.
Check power and cables
ReversibleCheck the power and the cables, and replace the WAN cable, and try another port on the modem.
Restart the modem
ReversibleRestart the modem for a few minutes, and then wait for it to reconnect to the provider.
Check the WAN address
ReversibleCheck the WAN address in the Internet settings of the Network application, and then test again to see whether it helped.
Test with a laptop
ReversibleTest with a laptop plugged into the modem, to see whether the provider's line is working.
Check DNS and ports
ReversibleCheck DNS and ports, using resolvers such as 1.1.1.1 or 8.8.8.8, and allowing UDP 53 and 123.
Reset last
ReversibleReset the gateway last, using the Reset button or the app, and only if nothing else has worked.
Model-specific
What is true of this model and not of its siblings
- Models
- The Dream Machine Pro is a rack-mount console, the Special Edition adds PoE ports and the Cloud Gateway Ultra is a compact gateway; techspecs.ui.com lists the ports of each.
- LED
- The blue and white LED patterns in Ubiquiti's article apply to all UniFi access points, routers, switches and the UDM base model.
- Other models this page answers
- These steps also fit the UniFi Dream Machine Special Edition, UniFi Cloud Gateway Ultra.
Stop boundary
When this stops being a self-service repair
- !If the gateway is dead with a good cable and port, request an RMA if it is in warranty
- !If a laptop on the modem has no internet, call the provider
- !If the gateway is up but unreachable, check TCP 8080 and the network path
Evidence ledger
Sources behind this answer
White, blue and port LEDs.
Cables, ports and RMA.
LED states, IP address checks and TCP 8080.
Reset button and app reset.
The company and its products.
Exact questions
Common questions
What does a flashing blue LED every five seconds mean?+
On a UDM, a blue light that flashes off every five seconds means there is no internet connection.
What does steady blue mean?+
A steady blue light means the device is adopted and is in its normal operating mode.
What does off mean?+
An off light means the device is offline, so check the power and the cables to it.
How do I get a replacement?+
You get a replacement through Ubiquiti's RMA portal, if the unit is within its warranty.
Which TCP port matters for management?+
TCP port 8080 matters for management, since devices reach the application on that port.
Can a private WAN address matter?+
A private WAN address suggests another NAT device in front of the gateway.
What resets the gateway?+
Use the Reset button or Factory Reset in the UniFi OS settings, to reset the gateway.
What does a steady white light mean on a UniFi device?+
A steady white light means the device is ready for adoption in the Network application.