Trying to Debug an OpenHAB Cloud EC2 instance

I am trying to debug an OpenHAB Cloud EC2 instance of one of my students. He modified some code to implement 2FA, but his instance always shows the local OpenHAB to be offline. It is clearly online, I can see and access it through my own openhabcloud.xxx.com, as well as through myopenhab.org.
I am using the exact same default and config.json file. I have checked that app.js is listening on port 3000. Nohup.out has no entry besides a warning that some mongodb feature is deprecated.
Here are the logs:

Openhabcloud.xxx.com-error.log

2024/11/30 19:24:51 [error] 1151#1151: *1 connect() failed (111: Unknown error) while connecting to upstream, client: 73.234.97.133, server: openhabcloud.xxx.com, request: “GET /socket.io/?EIO=3&transport=websocket HTTP/1.1”, upstream: “http://127.0.0.1:3000/socket.io/?EIO=3&transport=websocket”, host: “openhabcloud.xxx.com
2024/11/30 19:59:00 [error] 460#460: *1 connect() failed (111: Unknown error) while connecting to upstream, client: 73.234.97.133, server: openhabcloud.xxx.com, request: “GET /socket.io/?EIO=3&transport=websocket HTTP/1.1”, upstream: “http://127.0.0.1:3000/socket.io/?EIO=3&transport=websocket”, host: “openhabcloud.xxx.com
2024/11/30 20:00:00 [error] 1130#1130: *1 connect() failed (111: Unknown error) while connecting to upstream, client: 73.234.97.133, server: openhabcloud.xxx.com, request: “GET /socket.io/?EIO=3&transport=websocket HTTP/1.1”, upstream: “http://127.0.0.1:3000/socket.io/?EIO=3&transport=websocket”, host: “openhabcloud.xxx.com

Home.openhabcloud.xxx.com-access.log

205.210.31.18 - - [30/Nov/2024:19:50:52 +0000] “GET / HTTP/1.0” 401 12 “-” “Expanse, a Palo Alto Networks company, searches across the global IPv4 space multiple times per day to identify customers' presences on the Internet. If you would like to be excluded from our scans, please send IP addresses/domains to: scaninfo@paloaltonetworks.com

Openhabcloud.xxx.com-access.log

73.234.97.133 - - [30/Nov/2024:20:09:02 +0000] “GET /socket.io/?EIO=3&transport=websocket HTTP/1.1” 101 120 “-” “okhttp/3.8.1”

On the local instance, I found the following warning:
2024-11-30 15:04:00.637 [WARN ] [okhttp3.OkHttpClient ] - A connection to http://openhabcloud.xxx.com/ was leaked. Did you forget to close a response body? To see where this was allocated, set the OkHttpClient logger level to FINE: Logger.getLogger(OkHttpClient.class.getName()).setLevel(Level.FINE);

Any pointer to where the problem may be would be highly apprecitated.

Thanks,

Kristof