The earliest recollection of this bug is traced back to PAN-OS 11.1.13-h5. - July 31, 2026. This bug is fixed in PAN-OS versions 11.1.15., 11.1.13-h5.. ( Firewalls in Layer 2 mode only ) Fixed an issue where the new sessions were not able to be established due to the firewall intermittently dropping valid MAC address entries for specific VLANs when a manual switchover sent a high volume of traffic to the firewall. For more information: https://docs.paloaltonetworks.com/pan-os/11-1/pan-os-release-notes/pan-os-11-1-13-known-and-addressed-issues/pan-os-11-1-13-h5-addressed-issues https://docs.paloaltonetworks.com/pan-os/11-1/pan-os-release-notes/pan-os-11-1-15-known-and-addressed-issues/pan-os-11-1-15-addressed-issues