Wifi extender not working

I recently purchased a Dlink ac1720 Wi-Fi extender and after I complete the setup and do initial test, I find it severely lacks internet connectivity. Is there a reason a wifi extender won’t work with my dnsthingy Asus router setup? Also, should the WPS button work on the router to do secure setups of wifi devices? It doesn’t seem to work. Perhaps an updated router with stronger wifi signal would be the better option?