Basic URL loading on Android - can't resolve host

[Ben Rubinstein]

I've just started trying to create an Android app after a year or two. 
Restored Android studio etc, fine.

The first thing I try to do is load a simple URL. But I get
	tsneterr:(6) Could not resolve host: google.com

(or any other hostname from any other URL).

Using the browser on the device to access the same URL works fine.

Any URL I've tried has the same effect.

I've tried on another Android device, running a different version of Android - 
same effect.

I've tried de-selecting "automatic inclusion" and selected (among other things)
	Internet
	SSL & Encryption
	tsNet

What am I doing wrong?

TIA,

Ben