Local server accessible via SSL

I have a local server that is started with the command below:

java -cp /opt/LanguageTool-6.3/languagetool-server.jar org.languagetool.server.HTTPServer --languageModel /var/ngrams --port 8081 --allow-origin --public

It works well and responds to queries from server IP as below:

http://192.168.1.131:8081/v2/check?language=en-US&text=my+text

I also set up a reverse proxy using ngnix proxy manager forwarding the port 443 to the server’s port 8081. The domain name is registered as https://lt.example.net. When I try to access the language tool from internet using the following syntax, I get a 504 Gateway timeout error.

https://lt.example.net/v2/check?language=en-US&text=my+text

What am I missing?

I was able to figure out what my problem was. It was due to a firewall rule preventing communication between VLANs as planned. Once I put the server in the correct VLAN, everything started to work as expected. I am happy that both my firewall and my sanity passed this unplanned test, lol! I am sorry for occupying your time and space. Please mark this post now as SOLVED.