Found issue about internet connection lost

[cybernet2025]

I found the internet connection lost. When I found our workstation cannot access the internet. This is my step process that I've done.

1. Workstation cannot access internet and cannot ping 8.8.8.8 (request time out)

2. I've remoted to FG. (I can ping internal interface of firewall)

3. I'm able to ping 8.8.8.8 from FG

4. Workstation not able to ping 8.8.8.8

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I'm waited around 30 second and my internet is back. Workstation can access to the internet. I'm not sure what happened.

Could you please help me to find a root cause?

[Yurisk]

There could be too many possible reasons to be more specific, but I'd star with Fortigate logs - especially look in (System) Events logs at the time of the disconnection - if any interface went down, or IP pool/ports were exhausted, it would be recorded there. Also of use is the Routing Monitor - just make sure you have "Up Since" column set to display by right clicking (See screen attached), this will show for how long routes are in the routing table - if there were loss of connection to ISP, its route would have up time accordingly. 

[cybernet2025]

Yurisk wrote:

There could be too many possible reasons to be more specific, but I'd star with Fortigate logs - especially look in (System) Events logs at the time of the disconnection - if any interface went down, or IP pool/ports were exhausted, it would be recorded there. Also of use is the Routing Monitor - just make sure you have "Up Since" column set to display by right clicking (See screen attached), this will show for how long routes are in the routing table - if there were loss of connection to ISP, its route would have up time accordingly. 

1. I tried to find thr IP pool/ports were exhausted issue but I didn't see in Event log and CLI command by "diagnose sys session stat"

2. Port down issue I think it's now possible because when I found this issue I've remoted to firewall and I'm able to ping 8.8.8.8 from the firewall while client is not able to access the internet and can't ping 8.8.8.8 from inside.

[rwpatterson]

Look to see if resources at being taxed: CPU and memory during the episodes.