I can't get over the fact, that he is using "a public internet URL" to tunnel the traffic to his local server, just to watch it on his phone. What he should have done: - Make his local server listen on his local ip like <<local-lan-ip>>:3000 instead of just 127.0.0.1:3000 - Connect his cellphone to his local lan with wifi. - Look at the site on <<local-lan-ip>>:3000 on his cellphone.

I would never make a connection from a public Domain to my local machine just to test something. It's just too risky.