Troubleshooting Deco LAN speed is capped at 100m/s
Occasionally we received some feedback about the slow LAN speed from Deco and the typical description would be: "my internet bandwidth is over 200/500m/s, but I only got about 100m/s from Deco". After troubleshooting with different users, the following causes are confirmed to be relevant.
(Note, if the model is Deco E4, you might get the wrong model since Deco E4 is up to 100m/s.)
- The Total bandwidth under QoS is set to be 100/100 m/s.
If you happen to have the same case, please change it to be 1000/1000 m/s.
Visit this guide to configure the QoS settings on the Deco.
- The WAN link speed is capped at 100m/s.
The WAN link speed might be caused by different reasons. The first one would be the Ethernet cable between the modem and main Deco. Please replace it with a good quality Cat5e or Cat6 cable.
If in any case, the issue persists after checking the first two conditions, we need more information to locate the problem:
1. Are all the Deco units capped at 100m/s or just one of the satellite units?
(if it is only one of the satellite units, the troubleshooting guide here might not be helpful, please refer to this link: Why is my satellite Deco unit not getting the same speed as the main Deco?)
2. Please connect a laptop via Ethernet cable to the main Deco and check the link speed on the laptop to verify whether it is 1G or 100m/s.
3. A picture of your network layout, such as
We would love to hear more comments from your experience!
Related Articles:
Troubleshooting: Slow Internet Speed with Deco Devices
Why is my satellite Deco unit not getting the same speed as the main Deco?
Why the actual wireless speed on my wireless device is lower than the speed result on the Deco APP?
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@TP-Link i tried to connect my laptop and Cisco GE switch to DECO directly, only 100Mbps physical speed. tried with forced GE Full/Duplex on Cisco switch, then DECO disconnected.
GE is not true for this DECO M4.
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Hi @GeorgeZ, I have the same issue, I have 2 M4r Decos and 1 E4.
Hi @TP-Link
My connection is from Main router (ISP Router with 500 mbps speed) > Connects to M4 (Main router) via wired connection. > Both M4 and E4 are now connected wireless.
My two M4 Decos are working properly before using both free Rj45 Ethernet cable out from the box. I was able to get up to 300mbps before.
checked the internet speed and it shows that it accepts 1 GB connectivity. When I try to reboot the Decos, I get higher speed up to 200 mbps but it goes down after a while. May I know if there are solutions to this now?
M4 Current firmware: 1.5.1 Build 20210923 Rel. 55231. I tried to search for the latest patch but it shows it is updated to the latest.
E4 Current firmware: 1.6.1 Build 20231227 Rel. 53644.
What I do to get this speed again is to turn off (remove the power) for 1 minute. Then power it again. It will be now up to 350 mbps
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@TP-Link in my case I noticed that WAN is 100mbps only, on 1gbit WAN, disconnected WAN from Deco BE65, connected to another(second) Ethernet port and it connected at 1Gbit since. After that I connected Synology NAS to another port, it also connected on 1Gbit. So maybe there is some bug in Deco, but fortunately it can be solved by reconnecting Ethernet cables.
Anyone, don't try to replace your network cable, try disconnect and reconnect it first, much cheaper that way 😀. Also cat 5e/6 is enough for 2.5Gbit link. Don't buy cat 7 or 8, it may not work, and even if it will it's a waste of money. If You have 10gbit link, buy cat 6a cable.
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Hi, i have same problem in AP Mode! one day it sets itself to 1000 and the next day it goes back to 100! I think they are defective! this problem dates back to 2020. I changed switches, cables, I even tried to invert the decos. I inserted and removed cables continuously but nothing! None of this!. I have a switch connected to the ethernet port and when I try a speed test on another gigabit PC connected to the router (in the local network) I always find myself with a speed of 100Mb/S!. Incompetent technicians who do not try to fix this situation! who else is this situation happening to?
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@TP-Link I just setup the Deco xe200. I am connecting a PC to the satelite with a lan cable - tried both the 1gb port and the 10gb port. Sometimes I will get 850mbps download. but often it will be limited to just 50mbps download! (QOS is DISABLED) - and when I switch to WIFI it instanly goes to 650MBPS. what could the problem be???
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@john2353 Thanks for the solution. I've literally been looking for weeks on trying to figure out why my S4 mesh seemed limited to 250 mbps even after the ISP recently upped the speeds here to 400 mbps and finding an Ethernet-connected PC on a test was getting 460 mbps. I tried removing all QoS entries and setting it to 1000x1000... and STILL 250 Mbps. Then, I stumbled onto your solution of 999x999 and FINALLY! I get what I'm paying for. Thanks again...
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Have this same issue. Have two X50 connected via cable. And the sattelite Deco's cable clients are capped eventually. They start out OK but eventually they get capped.
Firmware: 1.6.1 Build 20241010 Rel. 65389
Have 1Gbps coming in and have access to it on the main Deco.
Have cable between main X50 and this specific X50.
When I first connect it, it's fine. Eventually the speed will cap at 100Mbps. While the cap is happening If I disconnect the same cable that comes from main Deco and connect it directly to my machine, it goes back to 900+.
Rebooting the Deco solves the issue but I already have a daily reboot, don't want to have to do it in the middle of the day as well.
QoS is disabled.
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The same happens with Deco M4 main unit - here.
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