Cannot complete installation - 502 Bad Gateway error

[Tomino2112]

I am trying to install JIRA on our server, but it so far it has been quite a nightmare...

Multiple times during the installation, we got 504 error and sometimes 502 error. When we get 502 the server becomes 100% unresponsive (just keeps giving 502) and I have to go and manually restart JIRA service.

I was still able to get to the point of setting up admin user, but now I am stuck at the last step of setup process, getting 502 error. I have restarted multiple times, completed same steps multiple times and still on the last step (the setup says "Setting up last step") I get 502. I wasnt able to go through that. 

I am using pretty standard AWS configuration with nginx as a web server.

Please help?

[Nic Brough -Adaptavist-]

What does the application log say?  And what is the memory/cpu usage when it appears to be stopping?

[Tomino2112]

CPU: ~ 35% but not every time I restarted Jira. nginx logs say that connection was refused and prematurely closed by jira. In catalina sometimes nothing, but couple of times I got insuficient memory for java runtime to continue