I don’t fullly understand your current situaution, are you running discourse behind proxy? if yes then probably you just need to expose port 80 and let your proxy server handle https/ssl.
Does that mean you deploying discourse on private cloud/on premise? If the answer is yes, then one common issue, is trying to access the site on LAN vs WAN, if this your cause and accesing the site from other network seems fine i.e. just try to access the site your mobile network then check this ref .
How is it set up, by discourse? If not by discourse then probably you only need to expose port 80.