This problem is that Ubuntu 16.04 LTS does not remember the WiFi password through a shutdown then a later restart.
Ubuntu 14.04 LTS had no problem with this. I let it upgrade me to 16.04 LTS (after making a backup, of course).
First impression is that I like it. It does take more RAM, but I can live with that.
Problem: WiFi is my only connection, and every time it is started up it is not connected to the net at all.
Clearly the service is running: It pops up a green box saying that WiFi networks are available.
When I click on the (up/down) icon in the upper right I see the list of routers.
Clicking on my router's name makes it pop up an empty box asking for the password. It just plan doesn't remember the setting.
I never had this problem with Ubuntu 14.04 LTS. It simply remembered and reconnected.
Due to the location of this computer, the environment gets way too hot during the day to leave it on all the time. It can only be used during the evening hours.
My question is in the title: How to make Ubuntu 16.04 LTS remember the WiFi password through a shutdown then later restart?