This method is applicable to
(CarlinKit 3.0/4.0/CP2A/A2A/U2W series)

Please turn on the browser's Incognito mode. After turning on the Incognito mode, try to enter the backstage again

Chrome Browse in private

https://support.google.com/chrome/answer/95464

Safari Private Browsing

https://support.apple.com/en-us/HT203036

If your Android phone still can't visit 192.168.50.2 using the above method, then please refer to this method

please ignore the box's Bluetooth signal and actively connect to the box's second WIFI with your phone. (WIFI name varies with the car model) 

It starts with VOL or Auto (password 12345678).

Input 192.168.50.2 with your phone's Safari browser.

Video Tutorial

U2W/CP2A Accessing web backend Tutorial for Android phone