No internet access after your end device (smartphone or computer) connects to the range extender. Check if the end device is set to obtain an IP Address automatically for the Wavlink ac1200 setup. Make sure the main router doesn’t enable any security settings, like MAC Filtering or Access Control. Connect the same end device to the main router directly to check its internet connectivity. Check its IP address and Default Gateway when connected to the router and range extender. Update the range extender to the latest firmware and reconfigure it using its WPS button.