HTTP 502 Server Hangup. What are the causes?

We are querying a node.js based server in our company and of the servers every so often throws a http status 502 after exactly 2 minutes saying "Server Hangup". I saw a lot of questions being asked on stackoverflow but I couldn't find a definitive answer. The way to reproduce this issue is doing an HTTP POST request to the server. The GET requests are fine.

I try the exact same requests to other similar servers and I've never got a 502. I have read everything about what 502 means but I am not sure what could be wrong with the server? Maybe a tcpdump on that ser开发者_JAVA技巧ver can be helpful? Could it be the server has too many connections and its not freeing them up? I would like to get some context before I email the other team with the problem.

Any feedback is appreciated.

Thanks, KA