WN3000RP range extender Windows Has Detected an IP Conflict!! Please Help

 Hello, I just bought WN3000RP N300 range extender to extend the wifi into my garage, and I got the WPS to work. So the extender is connected ot the router and I can connect to it with my computer. I can get into the menu and I can change the IP configuration.

However, This only works when the range extender is not physically plugged into my router with an ethernet cable.

The problem with using it this way is that it doesn't always work and it frequently drops connection and I have to reset both the extender and the router.

I read online that for best performance, I should have the extender plugged into the router via an ethernet cable. 

This is ok for me, as I dont expect anything better from a $30 device. 

When I plug the extender into the router, I can connect to it, I can go online just like when it's not physically plugged in....

BUT after 5 secodns, windows gives me a prompt 

"Windows Has Detected an IP Conflict"

And the connection drops. If I disconnect and reconnect again, the same thing happens.

This only happens when I have the extender plugged into the router.

I tried setting the extender to use DHCP and to use a static ip of 192.168.1.250  The same exact thing happened.

Please let me know what I need to do in order to use this device properly.

Thank you