WiFi connects but NO INTERNET

[netdog]

Since upgrading my mid-2010 Mini to Yosemite, the Wifi connects to my AE-based network, but there is a "!" in yhr middle of the WiFi indicator on the menu bar on the right meaning NO INTERNET. It isn't like some I've read that have Internet briefly or very slow. In my case, I never get Internet.

I can access the Mini via File Sharing when logging in as an admin, but Screen Sharing doesn't work since upgrading (settings seem okay). Apple's iOS Remote App also is no longer working.

All of my other devices and computers, including this rMBP running Yosemite, are working fine, but my Mini, which is my media server, is unable to connect to iTMS or any other Internet resources, and given the lack of Screen Sharing and Remote, I can only play music by actually going up to my TV (to which the Mini is connected) and using the local keyboard and mouse.

Help! Support.Apple.Com has been of no use, so I am counting on the wizards of MacRumors to bail me out.

 

[netdog]

And I've just discovered, no sound it seems. Music plays over HDMI through the TV but not out through the USB DAC sound device.

 

[Portaluk]

Same problem here on 2009 MBP, restarting temporally fixes issue but then it comes back after a random amount of time.
First I thought it was little snitch causing the issue, uninstalled that but same problem, factory reset router but same issue, all other devices connect fine though.
Just forgot all networks then reconnected been working fine for last hour or so have you tried that?