Clien is currently trying to install OpenShift 4.10/4.12 on a cluster at a large German datacenter operator (Hetzner) and are running into a network configuration issue that we hope you can help us with.

The main IP address of the dedicated root servers usually comes from a /26 or /27 subnet. To prevent the (accidental) takeover of foreign IP addresses, communication is only possible via additional gateway addresses.

The exact operator requirement is described at

https://docs.hetzner.com/robot/dedicated-server/network/net-config-cent-os/

.
We boot a server via PXE for installation with the following configuration:

append initrd=rhcos/v4.10/initrd.img,rhcos/v4.10/rhcos-live-rootfs.x86_64.img coreos.inst.install_dev=/dev/sda coreos.inst.ignition_url=

http://10.254.0

. 253/bootstrap.ign mem=4096M ip=144.76.26.120:144.76.26.97/32:144.76.26.97:255.255.255.255:node99994:enp27s0:none ip=:::::enp28s0:dhcp rd.route=0.0.0.0/0:144.76.26.97

Basically, the network configuration is as expected:

enp28s0 receives an address via dhcp.
enp27s0 gets the fixed IP 144.76.26.120, a route is created
However, the expected configuration of the PPP peer IP (144.76.26.97/32) does not take place:

```
[core@node99994 ~]$ ip a
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000
link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
inet 127.0.0.1/8 scope host lo
valid_lft forever preferred_lft forever
inet6 ::1/128 scope host
valid_lft forever preferred_lft forever
2: enp27s0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel state UP group default qlen 1000
link/ether 30:9c:23:83:65:66 brd ff:ff:ff:ff:ff:ff
inet 144.76.26.120/32 scope global noprefixroute enp27s0
valid_lft forever preferred_lft forever
3: enp28s0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel state UP group default qlen 1000
link/ether 68:05:ca:1e:3e:cd brd ff:ff:ff:ff:ff:ff
inet 10.254.0.6/24 brd 10.254.0.255 scope global dynamic noprefixroute enp28s0
valid_lft 80126sec preferred_lft 80126sec
inet6 fe80::6a05:caff:fe1e:3ecd/64 scope link noprefixroute
valid_lft forever preferred_lft forever

[core@node99994 ~]$ ip r
default via 144.76.26.97 dev enp27s0 proto static metric 100
10.254.0.0/24 dev enp28s0 proto kernel scope link src 10.254.0.6 metric 101
144.76.26.97 dev enp27s0 proto static scope link metric 100
```

The following configuration is expected
```
[cwx_service@node99994 ~]$ ip a
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000
link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
inet 127.0.0.1/8 scope host lo
valid_lft forever preferred_lft forever
2: enp27s0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP group default qlen 1000
link/ether 30:9c:23:83:65:66 brd ff:ff:ff:ff:ff:ff
inet 144.76.26.120 peer 144.76.26.97/32 brd 144.76.26.120 scope global enp27s0
valid_lft forever preferred_lft forever
inet 144.76.26.120/32 scope global enp27s0
valid_lft forever preferred_lft forever
3: enp28s0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP group default qlen 1000
link/ether 68:05:ca:1e:3e:cd brd ff:ff:ff:ff:ff:ff
inet 10.254.0.6/24 brd 10.254.0.255 scope global dynamic noprefixroute enp28s0
valid_lft 80126sec preferred_lft 80126sec
inet6 fe80::6a05:caff:fe1e:3ecd/64 scope link noprefixroute
valid_lft forever preferred_lft forever
[cwx_service@node99994 ~]$ ip r
default via 144.76.26.97 dev enp27s0
10.254.0.0/24 dev enp29s0 proto kernel scope link src 10.254.0.5 metric 100
144.76.26.97 dev enp27s0 proto kernel scope link src 144.76.26.120
```