TP-Link's own guidance separates the two red LED patterns. A solid red LED on the main Deco means it cannot reach the internet; TP-Link says this is usually a connection or configuration issue rather than a hardware fault. A pulsing red LED on a satellite means the satellite lost its link to the main Deco. For the main unit, TP-Link gives five steps. One, seat every Ethernet cable firmly and replace any that are old or damaged.
The checks in more detail
Two, confirm only the main Deco is connected to the ISP modem, because a satellite connected to the modem instead of the main Deco causes the red light. Three, connect a PC or spare router straight to the modem; if that has no internet either, call the provider. Four, change the DNS under IPv4 to 8.8.8.8 and 8.8.4.4 in the Deco app. Five, clone the MAC address of your old router or laptop to the main Deco with MAC Clone, which helps when the provider ties service to a device address.
Also power cycle the modem, and see whether a modem and router combination is doing its own routing, which creates a second network. If you see solid yellow, the Deco is starting up, so wait one to two minutes; if it never changes, power cycle it. If several devices in the home lose internet at once but the Deco light is not red, look at the modem's own lights and at your provider's outage page before changing Deco settings.
Keep a note of what the modem's lights show at the moment of failure, because TP-Link support and your provider will both ask for it. When you call the provider, say which lights the modem shows, that a computer plugged straight into it does or does not get online, and that the router in question is a Deco in Router mode; that saves the scripted questions about restarting equipment you have already restarted.
Differential
Likely causes of “TP-Link Deco mesh wifi has Wi-Fi but no internet”, and how to tell them apart
- 1
A loose or damaged cable
What separates it The main Deco shows a solid red light because the Ethernet cable to the modem is loose or damaged
How to confirm Reseat the Ethernet cable at both ends, or replace it with another cable, and check the light again
- 2
A satellite plugged into the modem
What separates it There is a red light with no internet because a satellite Deco was plugged into the modem
How to confirm Connect only the main Deco to the modem, and connect the satellites to the main Deco wirelessly
- 3
An ISP outage
What separates it No device on the modem has internet because the provider has an outage
How to confirm Call the provider, since the fault lies outside your home and outside the Deco
- 4
DNS problems
What separates it Websites fail to resolve because the DNS servers from the provider are not working
How to confirm Set the DNS servers manually to 8.8.8.8 and 8.8.4.4 in the Deco app, and test again
- 5
A MAC address the provider expects
What separates it The modem accepts only your old router because the provider tied the service to its MAC address
How to confirm Use MAC Clone in the Deco app to copy the old router's address to the main Deco
Before you touch a setting
Record this first — changing settings destroys the evidence
- The LED color and whether it pulses
- What is plugged into the modem
- Whether a computer works straight from the modem
- The name of your provider and the model of your modem
Try in this order
0 of 7 completedRead the LED
ReversibleRead the light on the main Deco, since a solid red light means that it cannot reach the internet.
Check cables
ReversibleCheck the cables between the modem and the main Deco, and reseat or replace any that look worn.
Check the connection
ReversibleCheck the connection, so that only the main Deco is connected by cable to the modem.
Test the modem
ReversibleTest the modem by connecting a computer directly to it, to see whether the internet works.
Change DNS
ReversibleChange the DNS by setting 8.8.8.8 and 8.8.4.4 in the Deco app, as TP-Link suggests.
Try MAC Clone
ReversibleTry MAC Clone, which copies the old router's MAC address to the main Deco for the provider.
Power cycle
ReversiblePower cycle by restarting the modem first, and then the main Deco, waiting for each to settle.
Model-specific
What is true of this model and not of its siblings
- LED patterns
- On the Deco M5, P7 and M9 Plus a solid red means an issue and a solid green means all is well; the X and BE series use pulsing and solid patterns as in the table.
- Deco M3W
- The M3W extender has separate power, signal and band LEDs instead of one color light.
- Other models this page answers
- These steps also fit the Deco BE63 mesh, Deco XE75 mesh, Deco X55 mesh, Deco M5 mesh.
Stop boundary
When this stops being a self-service repair
- !If a computer straight on the modem has no internet, call the provider
- !If the modem works but the main Deco stays red after all five steps, contact TP-Link support
- !If a Deco will not power on, replace it under warranty
Evidence ledger
Sources behind this answer
Five steps for a solid red main Deco.
Every LED color and pattern by model.
Main, satellite, client and random reboot fixes.
Reset versus reboot and the app and button methods.
The company and its products.
Exact questions
Common questions
What does solid red mean on a Deco?+
The main Deco cannot connect to the internet.
What does pulsing red mean?+
A satellite has lost its link to the main Deco.
What does solid yellow mean?+
Solid yellow means that the Deco is starting up, so wait one or two minutes.
Is a red light a hardware fault?+
TP-Link says that a red light is usually not a hardware fault, but a connection problem.
Should a satellite plug into the modem?+
No, only the main Deco should plug into the modem, and the satellites link to it.
Which DNS servers does TP-Link suggest?+
TP-Link suggests the DNS servers 8.8.8.8 and 8.8.4.4, which you set in the Deco app.
What is MAC Clone?+
It copies an old device's address to the main Deco.
Where do I change DNS?+
In the Deco app under More, Internet Connection.
Does resetting fix red?+
Try the other steps first, since a reset erases your settings and rarely fixes a red light.
What does a solid green or white light mean on a Deco?+
A solid green or white light means the Deco is registered and everything is working well.
What does a pulsing blue light mean on a Deco?+
A pulsing blue light means the Deco is ready to be set up in the Deco app.
What does a pulsing green light mean on a Deco?+
On X and BE series units, a pulsing green light means that the firmware is being upgraded.
How long should I wait after a Deco firmware upgrade?+
Wait about five minutes for the Deco to finish its upgrade and reboot before you test it.
How do I reboot the whole Deco network?+
In the app open the Network page, then the network map, tap the top right icon and choose Reboot Network.