NERFCapture connection to instant-ngp script on Ubuntu

[wetoo-cando]

I am trying to connect the NERFCapture iOS app to instant-ngp as described here:

https://github.com/NVlabs/instant-ngp/blob/master/docs/nerf_dataset_tips.md

I connected the PC to the iPhone hotspot. Then ran instant-ngp (with the --stream flag enabled) and the NERFCapture app on the iPhone. However no connection got established between the app and the script.

How should I connect the iPhone and the Ubuntu PC?
Does this work at all on an Ubuntu PC?