Hi @LeFagnard,

According to the translation of Google Translate, I think that your question is slow speed of powerline adapter. If there is any discrepancy, please describe it in English.

If you're experiencing low speed issues when connected to a TP-Link powerline device, 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: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.

 Hi @Joseph-TP 

All what you say is alwaye done. The problem apears only since 14 days. Before all was normal.
For the tests​​​​​, the placement is... on the same line on 2 meters one from another and on 50 cm from the modem...
I send in my first text the speeds. For 2,4 GHz, 5 GHz and LAN, its +- the same: slower han 2 Mbps in download and more then 22 Mbps in upload. The speed between the poweline extender and the "base" is more than 600 Mbps. The normal speed direct from the modem is download 75 Mbps and upload 27 Mbps.
If you can see, it is the download that has big problems.

Second poblem: I bought a new kit to ensure that nothing was wrong wis the old. Nothing has changed with the speed.

I can only access the settings on the new extender. All the older ones cannot be accessed (any more).
As I want to make my settings manually, this is a big problem.

 Hi @LeFagnard,

Please refer to case 2 of What should I do if internet connection is slow when the device is connected to TP-Link Powerline Adapters?

Please collect the result of powerline rate and wired link speed of end-device.

If both devices have the same problem, it is most likely that there is a problem with the current power line environment, not the Powerline device.

Hi  @Joseph-TP 

I repeat, all was fine 14 days ago. The problem for ALL the TP-Links is slow from one day to the next... without any change og whatever. The same sockets, the same line, the same modem...
Even if i put one extender in two power sockets on 30 cm one from another and take all the others out, the problem subsists.

Hi @LeFagnard,

I really hope to help you solve the problem, but whether it is your newly purchased Powerline adapter or the Powerline adapter that worked properly before, you have the same problem. This means that there is probably interference in the powerline environment, so I suggest you test the Powerline rate to evaluate the power environment.

If you insist that it is a hardware problem with the Powerline adapter, you can consider contacting your local support to consult warranty service.