Networking is where most new Proxmox installations stall: the install works, the first VM boots, and then "how do I give it an IP?" turns into an afternoon of half-matching forum threads. The underlying model is actually small: VMs plug into Linux bridges, and everything else is variations. This guide builds that model properly: what vmbr0 really is, bridged versus routed versus NAT setups on a hosting provider, VLAN-aware bridges, bonding done right, where the SDN layer fits, and how to change any of it without cutting yourself off.