Refer to the above link for deployment, and the installation process is all normal.
When Graylog is started, the service is fine.
However, system-nodes is “normal” for a while and "System information is currently unavailable "for a while.
Check log information as follows:
that single message does not help to identify possible issues. It could ne nearly everything. Started from a misconfiguration of Graylog, iptables or a full disk.
if you run alpha builds, you should be able to identify what is the issue by investigating and if you found a bug by reporting the issue at Github.