Mac not connecting to internet

The first thing I would try would be to forget the network and then add it again.

Make certain IPv6 is set to "link-local only" or off.

The next step is to use

system preferences > Network >Wi-Fi > (assist me) > ( diagnostics )

If no joy:

system preferences > Network > Wi-Fi > (assist me ) > ( assistant ) ...

... to set it up again from scratch, taking care to specify a new, named Network Location (NOT Automatic).

Using network locations (Mac OS X v10.6 and later) - Apple Support

.

I would recommend to join network automatically , location as automatic as compared to the settings in location as home or other . And keep DNS server settings 8.8.8.8 and 8.8.4.4 & make sure sure WPA2 personal AES as secured network is set , turn off proxy settings , create password for network . when click to advanced and click on wifi check the box remember network this computer has joined .

For modem provided by my service provider keep settings as automatic and check the box of firewall .

In air port utility , create a strong wireless network password , make sure block ipv6 , and the option as in screen shot as checked .

Some suggested articles : OS X El Capitan: Choose preferred wireless networks

: OS X El Capitan: Set advanced Wi-Fi options

Note : For guests they don't need password to login , if you are the administrator keep automatic login as off .

Thanks !