Hardware connections

• Are all of the cables and interfaces connected properly?
• Is the LED for the interface green?

FortiOS network settings

• If you are having problems connecting to the management interface, is your protocol enabled on the interface for administrative access?
• Does the interface have an IP address?

CPU and memory resources

• Is the CPU running at almost 100 percent usage?
• Is your FortiGate running low on memory?

Modem status

• Is the modem connected?
• Are there PPP issues?

Ping and traceroute

Is the FortiGate experiencing complete packet loss?

Logs

Do you need to identify a problem?

Contents of the routing table (in NAT mode)

• Are there routes in the routing table for default and static routes?
• Do all connected subnets have a route in the routing table?
• Does a route have a higher priority than it should?

Traffic routes

Is the traffic routed correctly?

Firewall policies

Is the correct firewall policy applied to the expected traffic?

Bridging information in transparent mode

Are you having problems in transparent mode?

Firewall session list

• Are there active firewall sessions?

Wireless Network

Is the wireless network working properly?

FortiGuard connectivity

Is the FortiGate communicating properly with FortiGuard?

Sniffer trace

• Is traffic entering the FortiGate? Does the traffic arrive on the expected interface?
• Is the ARP resolution correct for the next-hop destination?
• Is the traffic exiting the FortiGate to the destination as expected?
• Is the FortiGate sending traffic back to the originator?