Why is my internet connection slow when using a wireless extender?

Check the distance between the wireless extender and the router
The farther away the wireless extender is from the router, the more signal loss will occur, resulting in slow connection speeds.
Eliminate interference
Common sources of interference that may slow down your connection are microwaves, cordless phones and other electronic devices that use wireless networks.
Check the battery level
If the battery of the wireless extender runs out, it may cause connection problems.
Try a different source of power
Make sure the power source connected to the wireless extender is stable and secure.
Ensure that you are using the same Wi-Fi settings on the wireless extender
Using the same Wi-Fi settings (name, encryption settings, and password) on the wireless extender and the router will help the two devices communicate with each other.
Restart the router and the wireless extender
Restarting the router and wireless extender may help reset their connection and restore your internet speed.