How to access nginx server from outside using specific port (4430)


I’m trying to deploy a Flask app using nginx server. This server is hosted on one of my computers with an ubuntu system and using my internet connexion.

I managed to deploy the app and access it via my local network but not with others network. In order to do so, I tried to configure my box to allow remote access which is possible only through the port 4430.

Therefore I can pass the following test with success (using the port 4430):

My nginx configuration is the following one:

server {
    listen 80;
     listen [::]:80;
root /var/www/;
index index.html index.htm index.nginx-debian.html;


location / {
        try_files $uri $uri/ =404;


The app is still not accessible from others network when trying and I’m a bit confused about the manipulation needed in order to solve this issue.

I tried to change the nginx configuration file with port 4430 instead of 80 -> not working
I get “your connexion is not secure … NET_CERT_AUTHORITHY_INVALID”

I also tried to add a Self-signed SSL Certificate for Nginx using the following command:
sudo certbot --nginx -d -d

but I then get: “Timeout during connect (likely firewall problem)”

I’m quite new to that topic and any help would be very appreciated.

Hi @lou1

to validate your domain using http validation, a working port 80 is required. Perhaps with a redirect to another port 80 or 443, no other port.

Please start with some basics.

Then read something about challenge types:


doesn’t create a self signed certificate.

1 Like

@lou1 I’m not so sure from your story what the actual issue is here. Do you have trouble getting a Let’s Encrypt certificate? Or are you having trouble with installing a Let’s Encrypt certificate? Or is it more a “general” “how do I get nginx to work on another port” issue? Or perhaps a “how do I get my Flask app to do something” issue? Note: the latter two issues aren’t really issues discussed here on this forum if it doesn’t involve Let’s Encrypt. At least not in the “Help” section.

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