Local Network

Configure IPv4: Manually
IP address: 172.16.0.1
Subnet mask: 255.255.255.0
Router: (empty)

Troubleshooting

Plug a laptop directly into the Ethernet 4 port on elderflower. Set the network configuration on the laptop so that it is the gateway:

The IP of the machine is 172.16.0.10 — access the Proxmox dashboard at 172.16.0.10:8006.