Hi， the function of extender is not used to improve the speed, because it need to communicate with your main router ,and the device which connected to it, the speed will be slower in some degree. For your situation, you can try to stand at the same place and connect to your main router's Wi-Fi and test what's the speed and then do a compareation.

Hello, thank you, but I know by plugging my laptop into my router im getting 78meg, but when I test the xbox that's in a different room, im only getting 86% signal strength over the wifi, and a download speed of 25 meg, which im why in trying to hard wire it in, unfortunately I cant move either the router or xbox cheers

You can try to check the link speed, normally for wirelss connection, the real downlaod speed should be 60% of the link a speed, I find a FAQ on TP-Link Website for how to check the link speed https://www.tp-link.com/en/faq-2265.html