There's a fix in a related thread to this issue that let us be able to continue using the onboard broadcom NIC on a T440:
https://forum.proxmox.com/threads/proxmox-wont-complete-the-reboot.175419/post-873678
Ironically, AI actually fixed this for me and let me be able to continue to use the broadcom nic on a poweredge T440 that was having this issue. Looking around online, I didn't see any successful conclusion to this issue posted anywhere other...