Routed setup on Hetzner with Failover IPs: "Destination Host Unreachable

[Karcsi]

Message:

Hi,

I am having a massive headache with a routed network setup on a Hetzner dedicated server running Proxmox VE 9.2.3. I am running full KVM-based Virtual Machines (VMs), not containers, and I need to assign two separate Failover IPs to them without using NAT. I have been awake for days working on this every single night until morning because I need to get this working. I am incredibly frustrated and absolutely furious about this situation.

Setup details:

Host: Proxmox VE 9.2.3 (Clean factory-default network config).

Main IP: 88.198.41.200.

VM1 (Debian 12): IP 85.10.250.103/32.

VM2 (FreeBSD 14.4): IP 213.239.249.29/32.

Network: Standard vmbr0 bridge.

Note: I am not using IPv6, only IPv4. No MAC address binding is used.

The issue:
Even with a clean host configuration, the VM IPs are unreachable. Any ping attempt results in "Destination Host Unreachable". I have verified that ip_forward and proxy_arp are currently disabled, and the system is not routing the traffic to the VMs.

Request:
Since I am explicitly looking for a non-NAT solution, I need the complete, step-by-step list of commands and configuration file contents for the Proxmox host, Debian 12, and FreeBSD 14.4 to successfully route these /32 Failover IPs. I need a solution that works on a standard Hetzner environment without MAC binding. I am working on this all night, every night, and I am extremely stressed and angry. I really need a working setup that I can apply immediately to get this over with.

Any help would be incredibly appreciated.

Thanks!

 

[j.theisen]

Hi @Karcsi

thanks for posting in the forum!

Hetzner is sadly a little bit tricky to get up and running.
On a quick search for previous answers on this topic i found this post [1].
Maybe this can help you also.

Apart from that, may i ask why you need failover IPs on your VMs? They make the whole setup considerably more difficult.
Regular additional IPs could get a virtual MAC address assigned, which in turn can be assigned to the VM NIC to make the setup relatively easy.

Yours sincerely
Jonas

[1] https://forum.proxmox.com/threads/hetzner-and-failover-ip.18119/#post-412309

 

[Karcsi]

Hi Jonas,

thanks for the reply. I would prefer to stick with the routed setup for now, so I will pass on the virtual MAC approach.

I'd like to keep the details of my setup private, but I really appreciate your suggestion. Since I'm following the routed guide from post #7, could you help me figure out why I'm still getting "Destination Host Unreachable" from within the VM?

I have attached screenshots of my current configuration on both the host and the VM, in case you can spot any misconfigurations.

Thanks for your help!

 

[j.theisen]

Hmm, i tried replicating the situation locally but didn't succeed until now.
Also didn't see any obvious typos etc.

Just to be sure, you rebooted the PVE node after making changes to the interfaces file, correct?
What is the output of cat /proc/sys/net/ipv4/conf/vmbr0/proxy_arp

EDIT: Please also try a tcpdump on your PVE node for ARP messages
tcpdump -i nic0 arp

 

[Karcsi]

Yes, I rebooted the PVE node after the changes.

The output of cat /proc/sys/net/ipv4/conf/vmbr0/proxy_arp is: 1.qqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqq

It seems to be working now, please see the attached images. Thank you so much for your help! Regarding the FreeBSD machine, I'm not 100% sure yet if it's behaving exactly as it should, as I can only move the server files from my friend's machine this weekend. I will let you know if I run into any issues once the server is actually running.