Network Rules

Your server is connected to a shared data centre network. A few configuration mistakes on a Proxmox host can affect other customers. Our network detects them and automatically disables your switch port, which takes your server offline until our team intervenes.

Please follow these rules.

✅ Do

• Attach every VM to vmbr1 (or to vmbr2 if you use the OPNsense router).
• Use private addresses from 10.10.10.2 – 10.10.10.254 inside your VMs.
• Use port forwarding to make services reachable from outside.
• Contact support if you need additional public IP addresses.

❌ Don't

:::danger Never do any of the following

• Don't attach a VM to vmbr0. VMs on the public bridge expose unknown MAC addresses to our network and are blocked.
• Don't add IP addresses to vmbr0 or configure a public IP inside a VM. Using an address that isn't assigned to you causes IP conflicts with other customers.
• Don't add network ports to bridges. Your server may have a second network port (e.g. enp1s0f0). Adding it to a bridge can create a network loop.
• Don't edit or delete vmbr0. A mistake here locks you out of your server.
• Don't run DHCP servers or IPv6 router advertisements on vmbr0. They interfere with other servers on the network. :::

Why these rules exist

Mistake	What happens
VM attached to vmbr0	An unknown MAC address appears on our switch port and the port is blocked
Extra public IP configured	IP conflict with another customer or our gateway, and the port is blocked
Second NIC bridged	Network loop / broadcast storm, and the port is shut down
Rogue DHCP / RA on vmbr0	Other servers receive wrong network settings

Safe changes

You can freely:

• Create, change and delete VMs and containers on vmbr1
• Add port forwards to the vmbr1 section
• Create additional private bridges (with no physical port), e.g. vmbr2 for an internal network
• Use the Proxmox firewall to restrict access

:::warning Before editing network settings Always keep a copy of the working configuration:

cd /etc/network
cp interfaces interfaces.backup-$(date +%F)

If you lose access after a change, open a support ticket and we can restore access via the out-of-band console. :::