This is a clone of issue OCPBUGS-64645. The following is the description of the original issue:
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This is a clone of issue OCPBUGS-63007. The following is the description of the original issue:
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This is a clone of issue OCPBUGS-56783. The following is the description of the original issue:
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Description of problem:

OVN HCP cluster worker node  is unable to reach external network due to a missing NAT in the local cluster's(ACM) gateway router  for the specific HCP  worker node.

Non-working VM: 

1. ovn-nbctl lr-nat-list GR_host1.acp.example.net|grep 10.197.x.x

<No Output>

Working VM:

For the working VM, there is a correct NAT entry. 

[root@e35815ba6b1d ~]# ovn-nbctl lr-nat-list GR_host1.acp.example.net|grep 10.196.x.x
TYPE             GATEWAY_PORT          MATCH                 EXTERNAL_IP        EXTERNAL_PORT    LOGICAL_IP          EXTERNAL_MAC         LOGICAL_PORT
snat                                                         131.97.x.x                        10.196.x.x

Version-Release number of selected component (if applicable):

$oc get clusterversion
NAME      VERSION   AVAILABLE   PROGRESSING   SINCE   STATUS
version   4.17.15   True        False         13d     Cluster version is 4.17.15

How reproducible:

N/A - only OVN DB  and MG are available to  troubleshoot this issue. 

MG: https://attachments.access.redhat.com/hydra/rest/cases/04144466/attachments/b1174b1b-99bd-4c06-ab96-29ecf066fb89?usePresignedUrl=true