Admin Sessions Timing Out

My live FreePBX system keeps timing me out of my admin login at a much higher frequency than what it is set at.
System > Advanced Settings > Session Timeout (in seconds): 2592000
This should be 30 days, but I am often lucky to get 30 minutes. I tried re-saving the setting, and then also tried clearing the setting (“For unlimited clear this box and save.”), but it is still timing me out.
Any ideas?

Thought I would ping the community on this again. Any thoughts on why it would be timing out so often (or where to go look to further investigate), even with the session timeout setting set for what should be 30 days?

are you running a2billing on the same server?

No, I am not.