strange error with Fortigate 80C

Question

Dear Fortinet Support Team,

I would like to aking you about Fortigate devices problem.

Please check file attached & note listed below for more information.

1. Error: User cannot connect Internet

2. Troubleshooting

# Firstly, I connected directly between modem and personal laptop, Internet working normally. Therefore error not caused by Internet service provide (100% for sure).

# Sencondly, I tried to connect my laptop to Fortigate (via LAN port on Fortigae) Details: Internet -- Modem -- Fortigate 80C (LAN port) -- My laptop Result: cannot connect to Internet. (I also tried to reboot Fortigate devices, but nothing get better)

# Next step, I tried to check Cisco Switch Layer 3 (reboot, clear and reload configuration), due to 2 options

Option1 : Internet -- Modem -- Fortigate 80C -- Switch L3 -- My laptop : cannot connect Internet Option2 : Internet -- Modem -- Switch L3 -- My laptop : cannot connect Internet

# Finally : when I connect modem directly to Cisco Switch Layer 2, (now Modem working as a DHCP server), internet back to work normally !! Internet -- Modem (act as DHCP Server) -- Switch L2 -- My laptop In my opinion, error maybe caused by Fortigate devices (Sw L3 working normally).

Once time, I got an same error with Fortigate 80C, suddently usercannot connect to Internet . When I downgrade Fortigate's firmware to lower version, devices & internet back to work normally !!!

So, please kindly support me in this case. What I have to do to solve this problem? (Downgrade firmware? Re-config Fortigate by manual? Or any solution?)

Looking foward to hearing from you.

Thank you in advance.

ashukla_FTNT · Accepted Answer

Did you enable nat in policy ?Even though modem is doing nat it will only know about the 192.168.99.0 network (modem 1 case). So if have not enabled nat in firewall policy the traffic will go with original source address and that will be dropped by modem? Also make sure you have setup the route for the internal network 192.168.10.0 network if you are connecting devices behind the switch. If you still face the problem do the following from CLI: diag debug resetdiag debug disablediag debug enablediag debug flow filter addr 4.2.2.2diag debug console timestamp enablediag debug flow show console enablediag debug flow trace start 200 Now connect a pc directly to the lan of Fortigate and from pc's cmd run a ping to 4.2.2.2.You will see some debug output on fortigate CLI.stop the debug using the command: diag debug disablepost the output.

ashukla_FTNT · Answer

Post the following:1) Ip address details (pc, L3 switch, firewall, modem)2) Firewall interface and policy configuration3) Are you able to ping firewall lan ip from pc4) Are you able to ping modem ip from firewall CLi

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