The earliest recollection of this bug is traced back to PAN-OS 9.1.1 - July 29, 2024.
When you use a firewall loopback interface as a GlobalProtect gateway interface, traffic is not routed correctly for third-party IPSec clients, such as strongSwan. Workaround: Use a physical firewall interface instead of a loopback firewall interface as the GlobalProtect gateway interface for third-party IPSec clients. Alternatively, configure the loopback interface that is used as the GlobalProtect gateway to be in the same zone as the physical ingress interface for third-party IPSec traffic.
For more information:
https://docs.paloaltonetworks.com/pan-os/9-1/pan-os-release-notes/pan-os-9-1-release-information/known-issues/known-issues-related-to-pan-os-9-1-releases/pan-os-9-1-1-known-issues
https://docs.paloaltonetworks.com/pan-os/9-1/pan-os-release-notes/pan-os-9-1-release-information/known-issues/known-issues-related-to-pan-os-9-1-releases/pan-os-9-1-10-known-issues
https://docs.paloaltonetworks.com/pan-os/9-1/pan-os-release-notes/pan-os-9-1-release-information/known-issues/known-issues-related-to-pan-os-9-1-releases/pan-os-9-1-11-known-issues
https://docs.paloaltonetworks.com/pan-os/9-1/pan-os-release-notes/pan-os-9-1-release-information/known-issues/known-issues-related-to-pan-os-9-1-releases/pan-os-9-1-12-known-issues
https://docs.paloaltonetworks.com/pan-os/9-1/pan-os-release-notes/pan-os-9-1-release-information/known-issues/known-issues-related-to-pan-os-9-1-releases/pan-os-9-1-13-known-issues
https://docs.paloaltonetworks.com/pan-os/9-1/pan-os-release-notes/pan-os-9-1-release-information/known-issues/known-issues-related-to-pan-os-9-1-releases/pan-os-9-1-14-known-issues
https://docs.paloaltonetworks.com/pan-os/9-1/pan-os-release-notes/pan-os-9-1-release-information/known-issues/known-issues-related-to-pan-os-9-1-releases/pan-os-9-1-15-known-issues
https://docs.paloaltonetworks.com/pan-os/9-1/pan-os-release-notes/pan-os-9-1-release-information/known-issues/known-issues-related-to-pan-os-9-1-releases/pan-os-9-1-16-known-issues
https://docs.paloaltonetworks.com/pan-os/9-1/pan-os-release-notes/pan-os-9-1-release-information/known-issues/known-issues-related-to-pan-os-9-1-releases/pan-os-9-1-17-known-issues
https://docs.paloaltonetworks.com/pan-os/9-1/pan-os-release-notes/pan-os-9-1-release-information/known-issues/known-issues-related-to-pan-os-9-1-releases/pan-os-9-1-18-known-issues
https://docs.paloaltonetworks.com/pan-os/9-1/pan-os-release-notes/pan-os-9-1-release-information/known-issues/known-issues-related-to-pan-os-9-1-releases/pan-os-9-1-19-known-issues
https://docs.paloaltonetworks.com/pan-os/9-1/pan-os-release-notes/pan-os-9-1-release-information/known-issues/known-issues-related-to-pan-os-9-1-releases/pan-os-9-1-2-known-issues
https://docs.paloaltonetworks.com/pan-os/9-1/pan-os-release-notes/pan-os-9-1-release-information/known-issues/known-issues-related-to-pan-os-9-1-releases/pan-os-9-1-3-known-issues
https://docs.paloaltonetworks.com/pan-os/9-1/pan-os-release-notes/pan-os-9-1-release-information/known-issues/known-issues-related-to-pan-os-9-1-releases/pan-os-9-1-4-known-issues
https://docs.paloaltonetworks.com/pan-os/9-1/pan-os-release-notes/pan-os-9-1-release-information/known-issues/known-issues-related-to-pan-os-9-1-releases/pan-os-9-1-5-known-issues
https://docs.paloaltonetworks.com/pan-os/9-1/pan-os-release-notes/pan-os-9-1-release-information/known-issues/known-issues-related-to-pan-os-9-1-releases/pan-os-9-1-6-known-issues
https://docs.paloaltonetworks.com/pan-os/9-1/pan-os-release-notes/pan-os-9-1-release-information/known-issues/known-issues-related-to-pan-os-9-1-releases/pan-os-9-1-7-known-issues
https://docs.paloaltonetworks.com/pan-os/9-1/pan-os-release-notes/pan-os-9-1-release-information/known-issues/known-issues-related-to-pan-os-9-1-releases/pan-os-9-1-8-known-issues
https://docs.paloaltonetworks.com/pan-os/9-1/pan-os-release-notes/pan-os-9-1-release-information/known-issues/known-issues-related-to-pan-os-9-1-releases/pan-os-9-1-9-known-issues
