Network lost on Host when bridging physical interface

[vito974]

Hello everyone,

I'm struggling with a networking issue on a Proxmox VE 8 host hosted at Hetzner.

The problem: Everything works fine when the physical interface is configured directly, but as soon as I move the IP to a Linux Bridge (vmbr0), I lose all external connectivity (Host is unreachable and cannot ping 8.8.8.8).

My Setup:

• Hardware: Dedicated server at Hetzner.
• Interface: enp0s4
• Main IP: 95.217.144.57/26 (Gateway: 95.217.144.1)

What I've verified:

1. MAC Address: I have forced the bridge vmbr0 to use the same hardware MAC as enp0s4 using the hwaddress parameter.
2. ARP: Running tcpdump -i enp0s4 shows that ARP requests/replies are working. I see the gateway responding . I also see incoming traffic on port 8006, but the host doesn't seem to send anything back.
3. Routing: ip route shows the correct default gateway via vmbr0.
4. IP Forwarding: net.ipv4.ip_forward is set to 1.

My current /etc/network/interfaces:



Thanks for your help!

 

[Sviat]

Hi,

most likely Hetzner doesn’t accept the MAC/IP combination after you move the IP to the bridge.
Try to use a Hetzner vMAC or switch to a routed (non-bridged) setup.

 

[fmar]

Hello everyone,

I'm struggling with a networking issue on a Proxmox VE 8 host hosted at Hetzner.

The problem: Everything works fine when the physical interface is configured directly, but as soon as I move the IP to a Linux Bridge (vmbr0), I lose all external connectivity (Host is unreachable and cannot ping 8.8.8.8).

My Setup:

• Hardware: Dedicated server at Hetzner.
• Interface: enp0s4
• Main IP: 95.217.144.57/26 (Gateway: 95.217.144.1)

What I've verified:

1. MAC Address: I have forced the bridge vmbr0 to use the same hardware MAC as enp0s4 using the hwaddress parameter.
2. ARP: Running tcpdump -i enp0s4 shows that ARP requests/replies are working. I see the gateway responding . I also see incoming traffic on port 8006, but the host doesn't seem to send anything back.
3. Routing: ip route shows the correct default gateway via vmbr0.
4. IP Forwarding: net.ipv4.ip_forward is set to 1.

My current /etc/network/interfaces:

View attachment 95353
View attachment 95354
Thanks for your help!

Im facing the same issue on hetzner robot while reinstalling an old proxmox on the same hardware. Did you end up fixing this? If so, could you provide your config for reference?