Jira does not start properly after upgrading the server's memory

[br1984]

I noticed the server was running at >90% memory so I decided to add a gig of memory. After rebooting Jira no longer works. Error 521: Web server is down.  

When starting or stopping Jira with:

/opt/atlassian/jira/bin/start-jira.sh
/opt/atlassian/jira/bin/stop-jira.sh

Everything looks normal.  Jira appears to be running but there is no web access.  There are no errors, there is no information about what is going on.  Nothing was changed whatsoever except upgrading the server from 2GB memory to 3GB, otherwise the configuration is identical.

How do I fix this?

This is Jira 8.2.3
Running on: CentOS 7.5 x64

[Nic Brough -Adaptavist-]

A 521 error is not "server down", it's "I can't get a tcp/ip connection to the service", which is usually a network error rather than server.

Check the routing and firewalls between you and the server.

[br1984]

I guess cloudflare needs to update their error messages if that's true, but in this case the server was down. For whatever unkonwn reason it turned out that nginx stopped automatically starting on startup after the memory upgrade. I cannot figure out why, but manually starting nginx got Jira back up.

Thanks.