@MartiNGSQ 

Take a look at the bottom sticker of your router to determine the correct router model - it could be AX20, AX21, AX23, AX1800 or else.

When you determne the corrrect model, open the Global English support portal and and check if you hvae the latest FW for your model.

If not, then upgrade the router FW manually - details (Case 1).

Also make sure that you have not enabled/configured any QoS settings on your router.

Hi  @MartiNGSQ,

The speed you mentioned is the wired speed or wireless speed? If you are experiencing slow Internet speed with your TP-Link Archer Router, here are some steps to help troubleshoot the issue:
1. Please use https://www.speedtest.net or the speedtest APP/CLI(https://www.speedtest.net/apps) for testing speed accurately.
2. When testing with wireless, please connect your phone/laptop to the high speed network (5G/6G) instead of 2.4G. In order to reach maximum throughput over wireless, put the phone/Laptop next to the Router.

Here are some tips which might improve the speed of your Archer Router:
    1) If Ethernet speed is slower than expected, please try different Ethernet cables (CAT5E or above) on the Router.
    2) Disable QoS, please access http://tplinkwifi.net and go to Advanced >> QoS to disable it.
    3) Disable Parental Control, please go to Advanced >> Parental Control to disable it.
    4) If wireless speed is slower than expected, please go to Advanced >> Wireless Settings to change the 5GHz Wi-Fi channel, you may try different channels to find the best one for your environment.
    5) Disable SIP ALG and UPNP, please go to Advanced >> NAT Forwarding >> UPNP to disable UPNP, go to Advance >> Security to disable SIP ALG.
    6) Try a few other speedtest servers, other servers might reach better speeds.