Hi - I've been playing with using APN "internet" on One NZ (Vodafone). It allocates a public address and inbound is accessible. Sample test server on 443 is working (depending on incoming connection)

The problem is that its intermittant as to where the public address is acessible from.

I setup monitoring on the connection from a server in AWS Sydney so ping and 443 works. From Spark's fibre network its working in parts of the country, Cloudflare seems to work incoming BUT from Vodafones own 4G networking (using APN "vodafone") it does not work. Variable on Vodafones fibre network. 

Anyone know why this would be the case? 
I tested from various international connections and NZ connections as well as friends etc - and it works on some connections.

All through this testing - the connection is stable and remains connected so not like its loosing or dropping its connection or IP.