Dragino Yun and Uno serial issue

Hopefully I'm not posting to the wrong area or this question is too obscure... I'm a definite noob. My 13 year-old son (also a noob, but a smart one) is trying to control sketches on the Uno via wireless using a Dragino Yun shield. (we've done fine with just the Uno and with the Uno and an ethernet shield) He can do all the basic browser-based setup stuff with the Yun shield and the Yun shows up as a wireless port in the Arduino IDE (as flybot plus an ip address) but the USB port for the Uno doesn't show up under the serial ports menu. He tried running the examples wifi_status sketch and gets connection errors, we assume because there's no serial port connection to send the data back to the Arduino IDE.

The Dragino comes with a jumper you're supposed to place on the first pair of six headers nearest to the reset button on the Uno. If we connect the Yun with this jumper off, the Uno serial port shows up, but sketches hang during loading.

We've combed the forum and internet, but the explanations either don't seem to apply to Dragino setup or are way over our heads in complexity.

Can anyone help us get a toehold? Is it that working with the Yun is just too complicated for noobs?

I'm not familiar with the Dragino Yun shield. I wonder if it has taken over the Uno's HardwareSerial port (pins 0 and 1) for communication between the shield and the Uno.

That is how a "proper" Yun communicates with its Arduino - which is a real PITA.