Troubleshooting Tip: SD-WAN performance SLA down even though there is no actual packet loss (Known Issue #1023878)

[tino_p]

Description	This article describes how to troubleshoot unexpected behavior where the SD-WAN performance SLA is down even though there is no actual packet loss.
Scope	FortiOS versions 7.2.8 and 7.4.4
Solution	This is a Known Issue (#1023878) where SD-WAN Performance SLAs are failing despite there being no packet-loss. The issue affects FortiOS 7.2.8 and FortiOS 7.4.4, but not in any earlier v7.4, v7.2, or any v7.0 versions. When the issue is occurring, it is recommended to run the following commands: diag debug disable diag debug reset diag debug console time en diag sys sdwan health-check filter name [related_health-check_ID_here] diag debug app link-monitor -1 diag debug enable In the outputs of the above commands, any appearance of seq_no > 32768 with the keyword 'send probe packet, fail count' means this issue matches bug ID 1023878, which is resolved in FortiOS 7.2.9, 7.4.5 and 7.6.0. Upgrading FortiOS will resolve the issue. For example:   Related document: FortiOS 7.6.0 resolved issues.