Random Network Failures

Hi Damitha,
There can be many reasons why users/services experiencing dropouts.
1.During the outage, can you access other networks that are directly connected to the Fortigate, apart from the Internet link?
2.Do you see the same issue if you bypass the Fortigate?
3.The affected services, are they routed via a IPSec VPN ---> Datacenter ---> Internet or is it a direct link to the internet?
 
Best option will be to raise a support ticket with Fortinet TAC @ https://support.fortinet.com
 
Kind regards,
Rukshan

Since the outage is less than 5 seconds it is very hard to troubleshoot. But we started continues ping to internet, internel servers, other internel networks and during the outage there is no any timeouts. But SAP user sessions are disconnected. Same for the IP phones, FortiWiFis...
There are no IPSec VPNs. All the network segments are directly connected to the firewall. And 1 trunk port which has about 5 vlans. All the routing and access handled by the firewall itself.
There are no any event logs related to this. There were some logs related to webfilter, appfilter memory logs. I have disabled the memory logs for sometime, but the issue happened.
The unit has 3 VPN links, 3 Server Segments, 2 FortiWiFi subnets, 1 Trunk Port (all user VLANs), and 2 internet links configured for Wan link load balancing.

Hi
having only issue with traffic which is passing through fortigate?
or issue in the same subnet ? ( eg: connection lost between 192.168.1.1 to 192.168.1.2)
 
did you make any change in the global timer ?
check it
 
config system global
show full-config
 
 
Regards
Mahesh

Hi
See the below global timer settings


config system global
set tcp-halfclose-timer
set tcp-halfopen-timer
set tcp-timewait-timer
set udp-idle-timer

Did you make any change on this settings? Fortigate recommend this settings when device experience high cpu/memory usage.
Remember any changes done on this part?

Share the below command output

Config system global
Show full- configuration


Regards
Mahesh