

If it was a certificate issue I’d expect youd just get an error from your browser saying the cert is invalid or expired.
If I had to guess though you’re running into a nat reflection issue: https://nordvpn.com/cybersecurity/glossary/nat-loopback/
Read up on that. But you may need to provide different DNS entries if you’re inside or outside your LAN or add a NAT hairpin rule to your router. But this is only applicable if you’re exposing the same service to the WWW.
Some other things to try though:
- Have you tried just pinging the address? Is the DNS resolution returning the address you expect?
- Whats in your nginx logs? Do you see anything when you try and connect?
- Within your nginx container can you ping your service directly? Is something blocking nginx from accessing the site?
More technically there’s two ways to move data between two separate services. You can either pull or push the data.
Assume for both scenarios that the client is your phone and the server is some machine in the cloud.
With pulls the client calls an API and the server returns a response. Generally the www works this way. You ask a server for a wab page and you effectively pull the source down to your browser.
Pushes work the opposite, in that a server has data for the client and needs to push or otherwise give it to you. Pulls are relatively strait forward because every server has a well known name (the domain name and url). But your phone’s IP address changes constantly. So how does a server know how to contact your device? There’s generally two ways:
You could in theory implement either of these yourself but because of the way the OSes work on both Android and iOS there’s no guarantee that you can keep a process running in the background forever. As the OS can kill your process if the OS needs more free ram, etc … The built in notification APIs are exempt from this because they are part of the OS.