Strange thing ... after we moved the PBS physically to another place (and for sure, cabled to another switch) - all works well.
Before that, we replaced cables, installed a WLAN-adaptor, tweaked the networkinfrastructure and so on.
On the old...
There is also the manual (which you can also read from the Proxmox web GUI): https://pve.proxmox.com/pve-docs/pve-admin-guide.html#qm_pci_passthrough
Maybe just try selecting the 00:0d.0 device as a Raw Device when clicking Add > PCI Device in...