Ethernet not allowing internet access, Wifi does

System Preferences>Network, click on the little gear at the bottom next to the + & - icons, (unlock lock first if locked), choose Set Service Order.

The interface that connects to the Internet should be dragged to the top of the list.

In System Preferences->Network, do you see a green dot next to Ethernet? A yellow one?

Select Ethernet, and post a screenshot.

You can't go to Ventura, Monterey is the latest a 2014 can use.

Were you able to determine your Mini's Ethernet port is working?