@Jonathanlv 

Hi

There are several potential factors and troubleshooting steps you can take:

    1. Check powerline adapters' placement: Ensure that the powerline adapters are plugged directly into a wall outlet and not into power strips, surge protectors, or extension cords.

    2. Test different electrical outlets and move them into the same room for comparison.

    3. Check powerline rates between the powerline devices via tpPLC utility/App, you could refer to this FAQ to understand the difference between powerline rate and actual internet speed: https://www.tp-link.com/support/faq/2928/

If the powerline rate is too low, refer to this FAQ to see if it will be better: https://www.tp-link.com/support/faq/409/

    4. If the wired speed is normal, only wireless connection is slow, please try to change the Wi-Fi channel and channel width on the powerline extender.