Technical Tip: Daylight savings time changes and FortiGuard anycast DNS inaccessibility

[Adam_Shortt_FTNT]

Description	This article describes that some systems using anycast for FortiGuard connectivity may fail to reconnect to FortiGuard properly after significant time changes, like daylight savings time.
Scope	FortiGate systems using anycast for FortiGuard DNS or web filter services.
Solution	Changing the time zone to another zone and back may fix the issue without impacting other services.  If FortiGuard is configured to use Anycast servers (default), expect to see an IPv6 server with D I F flags when this command is run. The F flag means Failure: diag debug rating The issue was not observed when Anycast servers were not used: config system fortiguard     set fortiguard-anycast disable  set protocol udp  set port 8888  set sdns-server-ip 208.91.112.220 (other servers may also work) end Refer to this article for all of the protocol and port options when disabling anycast: Technical Tip: FortiGuard is not reachable via Any... - Fortinet Community. A fix for this issue also included disabling anycast and re-enabling it, done via the CLI. Alternatively, the urlfilter and DNS proxy services can be restarted to force a reconnection. In most circumstances this is non-impacting but a maintenance window is recommended: diagnose test app urlfilter 99 diagnose test application dnsproxy 99