FortiGate Firewall Troubleshooting - Internet Not Working (Basic)

In this article, we going to share the KB about How to kill the issues when you managing Fortigate Firewall from our real-time experience.

Troubleshooting based on firmware version FortiOS 5.4+


INTERNET NOT WORKING

    1) Check the routing table in Fortigate ISP route is updated or not.

     In GUI   goto Monitor > Routing Table > and check WAN's static-route is available or not.

     

     
         
If it is available, check IPv4 policy available for  LAN to WAN flow with NAT enabled.

If the static route is not available mean cross verify your routes written under NETWORK > STATIC ROUTE. 

if route also correct do source ping from WAN interface IP.( run the below-mentioned command as per the example)

Ex: WAN Interface IP: 122.122.122.121 | ISP Gateway IP 122.122.122.122

 # execute ping-option source 122.122.122.121                 /WAN Interface IP/

#execute ping 122.122.122.122                                         /ISP Gateway IP/

During the test, if you got the Ping-Reply from the gateway, again thoroughly check the above-mentioned steps. If everything correct do trace-Route (tracert) to 8.8.8.8 from user PC observe where the packet getting the drop, start to analyze from that node. 

NOTE: In the firewall route, policy, NAT everything working fine without any issues and able to ping 8.8.8.8 from PC then please check the DNS configured in the User PC.

revert if you have any doubt to our official email-ID mentioned in contact.