Client receives a guest VLAN address after an access port is assigned to the wrong VLAN
Trace a client that loses access to an internal web service through its DHCP lease, switch access VLAN, trunk and router ACL, then validate the port correction.
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vlanBuild a segmented small business network in Cisco Packet Tracer
Build and validate three VLANs, inter-VLAN routing, DHCP, internal and guest DNS, NAT/PAT and a minimum-access guest policy in a Cisco Packet Tracer lab.
FortiToken activation email fails: FortiGate SMTP local-out source IP
Troubleshoot FortiToken enrollment emails that time out on SMTP TCP/465 when FortiGate local-out traffic uses an unsuitable WAN source address.
Lenovo DE Series with VMware ESXi over SAS: fix single-path visibility, ALUA/NMP claiming and controller management
Troubleshoot Lenovo ThinkSystem DE Series storage connected directly to VMware ESXi over SAS when LUNs appear with only one path, devices show degraded status, volumes are not on the preferred controller, or ESXi reports HPP/NMP claim-rule conflicts.
Meraki mesh repeater fails 802.1X because the gateway AP is missing from Windows NPS RADIUS Clients
Troubleshoot a Cisco Meraki MR mesh repeater where normal SSIDs work but an Enterprise/802.1X SSID fails with RADIUS timeouts because the gateway AP is not registered as a RADIUS Client in Windows Network Policy Server.
FortiGate diagnose debug flow
Use FortiGate debug flow to trace how traffic is processed, routed, NATed, accepted, or denied by FortiOS.
FortiGate get router info routing-table all
Display the active FortiGate routing table and interpret connected, static, dynamic, and default routes during connectivity troubleshooting.
FortiGate get system arp
Display the FortiGate ARP table to map IPv4 addresses to learned MAC addresses and interfaces during local-network troubleshooting.
FortiGate IPsec tunnel is up but traffic does not pass
Systematically troubleshoot a FortiGate IPsec tunnel that is established but does not carry the expected application or subnet traffic.
Recover a failed FortiOS upgrade using the backup firmware partition
Recover a FortiGate that loses LAN connectivity after a firmware jump by booting its working backup partition from the serial console and then following the verified upgrade path.