[not really a bug] Installing on Proxmox/OVH [Soyoustart]

Steps To Reproduce

Installing the virtual machine with a failover IP on OVH/Soyoustart server does not work.
The VM start, but cannot resolve anything (no DHCP of course), neither the static IP configuration works (read below why and how to fix)

Expected Result

Be able to manually edit the .yaml (or choose some kind of checkbox to enforce this behayviour)

Actual Result

Impossible to activate NIC=> cannot configure the VM => abort

Screenshots, Videos, or Pastebins

No response

Additional Context

The problem lies in the peculiarity of the .yaml file to use a "strange" IP router, mandatory for OVH/Soyoustart
A "standard" OVH server have 1 "real" IP, and N "other" IPs (the failover).
The normal gateway is the IP.254

In this example the "first" IP is 176.178.179.180 => the gateway become 176.178.179.254
With a failover IP 37.1.2.3, on 00:51:52:53:54:55 (this is a ESXi legacy, whatever it is on proxmox)

The "routes" section is the key: it's mandatory (AFAIK)

Something like that (on ens19)

network:
   version: 2
   ethernets:
       ens19: #object name
         dhcp4: false # dhcp v4 disable
         dhcp6: false # dhcp v6 disable
         addresses: [37.1.2.3/32]
         match:
            macaddress: 00:51:52:53:54:55
         nameservers:
           addresses: [8.8.8.8,208.67.222.222]
         routes:
         - to: 0.0.0.0/0
           via: 176.178.179.254 
           on-link: true

My usual "quick-and-dirrrrrty" trick is

• control-C to enter "standard" shell
• changing the netplan .yaml by hand
• netplan apply
• launch another shell (alt f2)
• run the "normal" installation process

Of course, nothing impossible for a fairly experienced user, but I think it represents a blocking problem for those less accustomed
Kind regards

Build Version

25.0.2

Environment

By downloading the VM

Environment Details

• Proxmox 7.3.4
• Running on OVH/Soyoustart barematel
• 1 "real" IP + N failover, running on failover IP

Start by locating the netplan .yaml generation and the normal installation process in the VM scripts. Reproduce the Proxmox/OVH failover-IP setup, then determine how manual routing with an on-link gateway can be selected or preserved; done means the VM activates its NIC and completes installation without editing the YAML in a shell.