Umm… curious. I cant replicate a time out right now, but I had those before. Cant remember what I did to fix it. What I can remember was checking the following.
Selinux - I had to excute “root # sealert -a /var/log/audit/audit.log” I did find some warning/s.
Firewall - I checked for errors or warnings in the logs.
Reverse Proxy - ( i.e. nginx) At one point I removed nginx and just ran Graylog HTTPS. This person post also showed without reverse proxy it worked, maybe same?
File Permissions - I check to make sure Graylog had permission to the files it needed ( keystore, etc…)
I monitored my graylog-server while loading the dashboard to see if I needed more resources.
I used the command “iotop” the same way to identfy long wait times that stuck out.
Other then that, Im not to sure.