A customer purchased an HPE ProLiant DL380 Gen10 Plus and I installed ProxMox VE 8.0, however, after installation it does not work on the network.I edited the /etc/network/interfaces file and set it to static and still all connections are DOWN.
You checked ip a for "NO-CARRIER" and if the interface names match your /etc/network/interfaces?
Maybe your editing of the /etc/network/interfaces wasn`t correct? You didn't gave as any configs so it's hard to tell.