Hi, thanks for your reply. I did what you asked, the newly created file is attached to this post.
With your input I was able to solve the problem for my particular use-case. I'm passing through the adapter to a VM, but its "remains" in the Unraid System kept me from configuring the network routes to my liking.
By appending "iommu=pt xen-pciback.hide=(00:1f.6) vfio-pci.ids=8086:15b8" to the Syslinux config, then deleting "network-rules.cfg" and rebooting, the interface no longer appears in the networking settings or Dashboard. So I'm happy now, thanks.
The problem in general remains though.
network-rules.cfg
network-rules_with_passthrough.cfg