R8000 router acting weird suddenly

Suddenly the router is blocking my phone from being connected to the WiFi. When I login to routerlogin.net  using my laptop and chrome, I can access the router. But if I make any changes and hit 'apply' all I get is a spinning circle. If I try to log out nothing happens. If I close the browser window then try to login to the router again, I get an alert saying the request timed out and the router can't be accessed. So I reboot the router by unplugging it and then plugging back in. Then I can access routerlogin.net again. But again if I try to make any changes on the router, this cycle happens again.

Also the only way I was able to get my phone on the WiFi was disabling Auto Access on the router. Then my phone wasn't blocked.

Please help. I really don't like leaving access to my WiFi open to any devices connecting unless I ok them. And I don't want to have to reboot the router every time I want to make changes on the router.

Thanks