If your router has two settings, please enable the 2.4 GHz frequency band. Make sure your router is set to 802.11 mode and wireless setting is b/g/n mixed. Make sure your router has the SSID Broadcast function enabled when you connect the machine with the app. Make sure DHCP function is enabled. If you changed your Wi-Fi network, you need to connect your Landroid to the new network.
Possible cause:
Incorrect settings.