Mac Mini, El Capitan - Ethernet card not found

I found bits of info here and there on other posts but...
I have a late 2012 mac mini, 16g of ram, el capitan. After booting up the computer yesterday, it would not see it's own ethernet card. Checked the cords and the router. Booting back up with the PRAM buttons, I used the utilities screen to reinstall a fresh El Capitan. It downloaded it so, yes the ethernet card was ok. The reinstall worked.

Is there an issue(s) with El Cap & Mac Mini & Ethernet or some combo of those? Can I head this off or see it coming next time?