@Heinzipopeinzi 

Good day.

Thank you very much for your time and patience.

Sorry for the delay.

How long have you had the extender and did the speed get slow since you bought it？

TL-WA850RE provides 300Mbps wireless associated speed and 300Mbps needs to be used to communicate with router and PC that linked to the range extender, Therefore, data from router to PC passes through the WA850RE and WA850RE needs to “receive” data from router first then “send” it to PC. Due to half-duplex system, “receive” and “send” cannot be carried out simultaneously. In that case, its maximum is 150Mbps at one direction because half of the time PC needs to wait for WA850RE to receive data from the router and WA850RE cannot send data to PC at that moment.

Also considering the Wi-Fi interference and communication loss, the final internet download speed would be around 75m/s.

If possible, please check the Ethernet speed from the 850RE as well to see how much it is;

And change the wireless advanced settings on the main router, such as channel 1/6/11 for 2.4ghz to reduce the Wi-Fi interference;

Furthermore, since your total bandwidth is around 209m/s, TL-WA850RRE might not be the proper device for you.

If you just bought it, you could return it and get another model, such as RE300 or RE305;

Thanks a lot.