on macOS in app root dir and while iOS simulator opened:
mac$ exp ios
15:37:20 [exp] There is a new version of exp available (52.0.3).
You are currently using exp 51.4.0
npm install -g exp to get the latest version
15:37:23 [exp] Making sure project is set up correctly…
-15:37:24 [exp] Warning: You are using npm version 5.6.0. There may be bugs in this version, use it at your own risk. We recommend version latest.
15:37:35 [exp] Your project looks good!
15:37:37 [exp] Opening exp://localhost:19000 in iOS simulator
I see in simulator:
could not connect to the server