TP-Link says Deco slowness comes down to three things: placement, a device limit, or a misleading test. Place every Deco in open space, never in a closet or TV cabinet. For a wired test, make sure the cable and PC match the LAN port speed, since a 100 Mbps port caps results near 90 Mbps regardless of plan, and use Cat6 or better for 2.5 Gbps and up.
The checks in more detail
For a wireless test, disconnect other wireless devices first, and reconnect to wifi before each test because some devices hold a connection to the wrong node. The app's Test Internet Speed under Deco, Network measures only the main Deco's connection, not what a device gets. Test in order: plug a gigabit PC into the modem and run Ookla Speedtest; then plug it into the main Deco; then test wireless. If the main Deco is slow, there is a main Deco guide; if only a satellite is slower, there is a satellite guide.
TP-Link also lists turning off QoS in the app (More, QoS) and turning off UPnP and SIP ALG under More, Advanced, NAT Forwarding as common fixes for slow wireless, and notes that with Ethernet backhaul all units should show the same speed. Older laptops may not support 5 GHz or fast rates. Do not judge the network from a single test. Run the wired test and the wireless test at least twice at different times, write down each result, and compare them with the plan speed on your bill.
A wireless result of roughly half of a wired result is normal on many phones, and only a large gap points to placement or a fault. Speeds also vary with the time of day because the whole neighborhood shares the provider's network. A test at 8 pm can be far lower than one at 6 am without anything being wrong at home.
Differential
Likely causes of “TP-Link Deco mesh wifi internet or Wi-Fi is slow”, and how to tell them apart
- 1
An enclosed Deco
What separates it The wifi is weak and slow because a Deco is enclosed in a closet or a cabinet
How to confirm Move the Deco into the open, at about the same height as the other Decos
- 2
A 100 Mbps port or cable
What separates it The wired results are near 90 Mbps because the port or the cable only runs at 100 Mbps
How to confirm Use gigabit equipment and a Cat6 cable, and test the wired speed again
- 3
Other devices using bandwidth
What separates it The test reads low because other devices are using bandwidth at the same time
How to confirm Disconnect the other devices for the duration of the test, and run it again
- 4
A device on a far node
What separates it One device is slow because it is connected to a node that is far from it
How to confirm Reconnect the device to the wifi, so that it picks the nearest node
- 5
QoS, UPnP or SIP ALG
What separates it The wireless speed is reduced because QoS, UPnP or SIP ALG is switched on
How to confirm Turn those features off as a test, and see whether the wireless speed improves
Before you touch a setting
Record this first — changing settings destroys the evidence
- Speed at the modem, at the main Deco and on wifi
- The speed of the port and the cable used for the test
- Which node the slow device uses
- Whether QoS is switched on in the Deco app
Try in this order
0 of 7 completedPlace Decos in the open
ReversiblePlace the Decos in the open, and never in a closet or a TV cabinet.
Test at the modem
ReversibleTest at the modem with a gigabit computer, using an Ookla speed test for the reading.
Test at the main Deco
ReversibleTest at the main Deco with the same computer and the same cable, and compare the results.
Test wireless
ReversibleTest wireless by disconnecting other devices, so that the test has all of the bandwidth.
Reconnect before each test
ReversibleReconnect the device before each test, so that it does not stay on a far node.
Turn off QoS, UPnP, SIP ALG
ReversibleTurn off QoS, UPnP and SIP ALG as a test, and see whether the speed improves.
Compare units
ReversibleCompare the units, meaning a satellite against the main Deco, to find any weak unit.
Model-specific
What is true of this model and not of its siblings
- Ports
- The Deco BE85 has 2 x 10G and 2 x 2.5G ports; the X55 has gigabit ports.
- Wi-Fi standard
- Wi-Fi 7 needs a Wi-Fi 7 device to see the top speeds.
- 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 the modem tests slow on a PC, call the provider
- !If the main Deco is slow wired, contact TP-Link support with the results
- !If only a satellite is slow, check its backhaul and placement
Evidence ledger
Sources behind this answer
Testing correctly and isolating slow speeds.
Main Deco slow speed.
Satellite slower than the main.
Height, interference and signal bars.
The company and its products.
Exact questions
Common questions
What does the app speed test measure?+
The speed test in the app measures the main Deco's connection to the internet only.
Why is my wired result capped?+
A 100 Mbps port caps near 90 Mbps.
Which cable for 2.5 Gbps?+
Use a Cat6 cable or higher, since it can carry a speed of 2.5 Gbps.
Should other devices be off?+
Disconnect them for a wireless test.
Why reconnect before a test?+
Some devices hold a far node.
Can QoS slow wifi?+
Turning it off is a listed fix.
What is SIP ALG?+
A NAT feature TP-Link lists as safe to turn off for speed tests.
Do satellites match the main speed?+
With Ethernet backhaul, the satellites should give about the same speed as the main Deco.
Do old laptops limit speed?+
Yes, some old laptops limit the speed, since they lack support for the 5 GHz band.
Which features vanish in Access Point mode?+
Antivirus, parental controls, QoS, port forwarding, address reservation and DDNS are not available in that mode.
Does the Deco app need a TP-Link ID?+
Yes, you need a TP-Link ID for setup and for managing the Deco from the app.
What is Ethernet backhaul?+
It means connecting the Decos to each other by cable, which gives a faster and steadier mesh.
What is the reboot schedule on a Deco?+
It is a Deco option that restarts the units on a timetable, for example at night.