Try this:
Select your WiFi connection in Network Manager and apply these settings:
“All users may connect to this network”
“Automatically connect to this network when it is available”
“Store password for all users (not encrypted)”
Then, reboot.
Note:
Storing your password unencrypted is a slight security risk if others have physical access to your computer.
There is a possibility others who use your computer may be able to find your WiFi login credentials if it is not encrypted.
Also if you do not already have it installed, it might be advisable to install "nm-connection-editor" and enter your password for your connection directly from within that utility. After installation start NMCE with the command "nm-connection-editor" via the terminal.