@LaurieUK 

Hello，

For the slow speed issue, please try the following the suggestions:

1. Please only connect one end-device to the powerline unit by cable/WIFI and check whether the wireless or wired speed is slow? 

2. Please try the troubleshooting steps in this FAQ:  https://www.tp-link.com/en/support/faq/2231/

3. Please relocate the Powerline units in the same room or plug into the same power strip to do the test speed again.                                                                                                                                                                                                         

(Note: during speed tests, do not run any high bandwidth activities like P2P download, gaming, or video streaming.)

If the issue persists, please let us know the troubleshooting steps you have tried in details and help confirm some information:

1. Please send us the Photos of speed test results from the main router and Powerline units.

2. The photo of the Powerline rate on tpPLC Utility.

3. May I know the hardware on the label of the powerline unit and the firmware version on tpPLC Utility?

4. When did you buy the powerline devices and when did the issue begin?

5. Y  ou have mentioned that the powerline product is rather hot, please locate the router under a cool and well-ventilated environment, that is to say, put it under the open area, not cover it with any objects, avoid direct heat or excessive sunlight. Then check if it can work well. 

May it help and have a nice day!