wi fi - Galaxy S6 and S7 not auto-connecting to WiFi

I've had a problem with my phones (Galaxy S6 and S7) not auto-connecting to WiFi. When I open up the WiFi settings it will connect.

Is there any way I can determine if an app is disrupting the ability to auto-connect?

I think it is not the phone because I just got a new S7.

I think it is not the router because this happens with multiple routers.

Thanks very much for your help.

Edit: This is close to being a duplicate of
AT&T Samsung Galaxy S6 will not connect to WiFi automatically and

Galaxy S6 no longer automatically connects to my home WIFI

Edit 2: I have uninstalled a bunch of apps on my S6 and it now auto-connects without issue!

Edit 3: I have uninstalled a bunch of apps on my S7 and it now auto-connects without issue!!

Answer

This appears to be a problem with app interference. I have uninstalled a bunch of apps on my phones and they now auto-connect without issue.

I wish I knew which app or apps was the culprit. As I install back some apps that I need maybe I will find out. If I do I will update this answer.