The earliest recollection of this bug is traced back to PAN-OS 8.1.10 - January 09, 2024. This bug is fixed in PAN-OS versions 8.1.10. ( PA-800 Series firewalls only ) Fixed an intermittent congestion condition caused by paused frames on firewalls where flow control was enabled on adjacent firewalls. To leverage this fix, run the set system setting hol-system enable CLI command to enable head-of-line (HOL) system mode. For more information: https://docs.paloaltonetworks.com/pan-os/8-1/pan-os-release-notes/pan-os-8-1-addressed-issues/pan-os-8-1-10-addressed-issues