Troubleshooting What if LAN Speed of the Wi-Fi Router Is Capped at 100 Mbps?
This Article Applies to:
TP-Link Routers
Issue Description/Phenomenon:
Some customers may report the associated/link speed between their computer and the router is capped at 100 Mbps, thus they cannot get the expected bandwidth from the ISP even though they paid for 500+ Mbps or 1 Gbps. However, they can get the desired speed when connecting to the ISP modem directly, or connecting to the 5GHz network of the TP-Link router.
If the above issue is what you are experiencing, follow this article to get it resolved.
Troubleshooting Suggestions:
1. Determine if the WAN/LAN ports of your TP-Link router support 1 Gbps or 2.5 Gbps. Some models like Archer C20 and Archer C50 only support 10/100 Mbps WAN/LAN ports, you can find that in the product specifications here and here. If your router only has 10/100 Mbps WAN/LAN ports, you cannot get a higher speed than 100 Mbps, and you need to get a gigabit router.
2. Be sure you can get the desired speed when connecting to the ISP modem directly, and the Internet Negotiation Speed is 1000 Mbps on the router web page. You can check it by navigating to Basic > Network Map > click on the Icon for TP-Link router, you will see the page as follows:
If the Internet Negotiation Speed is capped at 100 Mbps, please follow this thread to troubleshoot.
3. If the above two are confirmed without an issue, please ensure the computer or device that connects to the router LAN port supports 1 Gbps. Check the computer specifications or contact their support if you are not sure.
4. Try with another Cat 5e/6 cable between the router LAN and the computer, or change the LAN port of the router.
5. Test with another gigabit device.
6. Try to reset the router to the default factory following the FAQ.
7. Upgrade the router firmware to the latest. You can follow this guide.
If in any case, the LAN speed still gets stuck at 100 Mbps after checking all the above, it is suggested to comment below and be sure to provide the following information:
1. Model number, hardware, and firmware version of your TP-Link Router.
2. What troubleshooting have you done, and what are the results (Screenshots)?
3. What are the devices that you are testing the LAN speed, and what are the models of the adapters?
4. When did you purchase the TP-Link router, and when did the issue begin to happen?