Fortigate 500D stops passing traffic from a DMZ

[boozely25]

I am running 5.6.3 on a stand alone Fortigate 500D.

I can ping and connect to anywhere I need to from my dmz. Every 20 minutes my Fortigate will stop passing traffic. Pings from a dmz machine to a dmz machine work. Pings from the firewall interface connected to the dmz to any dmz machine work and vice versa. However, when I try to ping from the dmz to anything else it fails.  After 20 minutes has passed, the pings to devices located outside the dmz start working again. Has anyone seen this behavior from a Fortigate before.  FYI...I was running 5.6.2 and I was seeing this behavior. It carried over to 5.6.3.

Thank you

[emnoc]

cli cmd "diag debug flow" is your friend; execute this when the problem arises

Or side note have you enabled  logging and look for any system event log messages? Maybe the  system is exhausted in memory or running in conserve mode, maybe the links are unstable, etc.......

Ken