Hi @Robin33,

The specification that starts with AV is the maximum powerline rate which will be shown on the tpplc utility, instead of the actual speed. And the powerline rate displayed on the PLC utility is the theoretical negotiation speed between the two powerline adapters, due to the interference with the powerline environment, the real powerline rate  will not reach maximum powerline rate. However, the conversion rate (The ratio of transmission rate and Powerline rate) is about 30%-35%(the actual conversion rate depends on the electric wiring system).
Let's take TL-WPA8630KIT(TL-WPA8630 & TL-PA8010) as an example. Although the maximum powerline rate is AV1300, the real powerline speed shown on the tpplc utility is only 500 Mbps. The conversion rate is 30%-35%, so the actual throughput should be about 150Mbps-175Mbps.
If you combine powerline devices with various powerline rates, the maximum powerline rate  will be limited by the lowest one. For example, if you pair an AV2000 with an AV600, their powerline rate cannot exceed 600Mbps.  
For more details, please refer to the FAQ: Explanation about the Powerline Rate and Actual speed of the Powerline Adapters

 HI @Robin33,

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.If the powerline rate is too low, refer to this FAQ to see if it will be better: What can I do if my powerline rate is very low?
    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.
    5. Check available firmware updates and ensure the powerline adapter and extender are both using the latest firmware.