@Relic 

The powerline link speed displaying on the tpPLC utility is not the actual speed you can get, while it does affect the actual speed. We can do some troubleshooting to locate this issue and try to fix it. 

1. What is the current hardware/ firmware version of the TL-PA7010KIT?

2. Try to change another computer and connect it to the powerline adapter by wired cable to test the speed. Please check the wired negotiation speed as the instruction.

Note: The steps are the same, but you need click ethernet connection.

3. Try to swap the two adapters to give it a go. 

4. You can hard reset it and change another socket to plug them also. 

Good day. 

@Relic 

Thanks for your reply. 

The current firmware is the latest one already. After you hard reset it or change another socket, does it become better? 

Besides, you can plug them into the same room and test the speed. 

Good day.