According to the information you provide, it is recommended that you click Settings - WLAN-Advanced Settings to select Never sleep, and click Settings -wlan- to find this wifi, click the small arrow on the right, do not save the network,
Try to re-enter the password, you can also try to restart the router to try, if the problem still occurs, it is recommended that you try the wifi network of other environments to see if the problem still occurs. I hope the above information can help you, wish you a happy life! Thank you!