Connectivity issues after upgrading to OpenShift Container Platform 4.6.9

Issue

• After upgrading OpenShift Container Platform from 4.6.6 to 4.6.9 we experience random connectivity issues in certain Pods.

• For example, the authentication-operator is reporting the following error messages:

  [..]
  status:
    conditions:
      - lastTransitionTime: '2021-01-07T09:38:22Z'
        message: >-
          OAuthRouteCheckEndpointAccessibleControllerDegraded: Get
          "https://oauth-openshift.apps.openshift.example.com/healthz": context
          deadline exceeded (Client.Timeout exceeded while awaiting headers)
        reason: AsExpected
        status: 'False'
        type: Degraded
      - lastTransitionTime: '2021-01-07T09:34:03Z'
        reason: AsExpected
        status: 'False'
        type: Progressing
      - lastTransitionTime: '2021-01-07T10:23:00Z'
        message: >-
          OAuthRouteCheckEndpointAccessibleControllerAvailable: Get
          "https://oauth-openshift.apps.openshift.example.com/healthz": context
          deadline exceeded (Client.Timeout exceeded while awaiting headers)
        reason: OAuthRouteCheckEndpointAccessibleController_EndpointUnavailable
        status: 'False'
        type: Available
  [..]
  

• Other symptoms include DNS errors such as "no such host" in multiple components:

  E0107 11:30:48.746431       1 base_controller.go:250] "OAuthRouteCheckEndpointAccessibleController" controller failed to sync "key", err: Get "https://oauth-openshift.apps.openshift.example.com/healthz": context deadline exceeded (Client.Timeout exceeded while awaiting headers) 
  [..]
  2021-01-07T16:24:40Z auth: failed to get latest auth source data: request to OAuth issuer endpoint https://oauth-openshift.apps.openshift.example.com/oauth/token failed: Head "https://oauth-openshift.apps.openshift.example.com": context deadline exceeded (Client.Timeout exceeded while awaiting headers)
  2021-01-07T16:30:13Z Failed to dial backend: 'dial tcp: lookup kubernetes.default.svc on 10.140.0.90:53: no such host'
  2021-01-07T16:30:33Z Failed to dial backend: 'dial tcp: lookup kubernetes.default.svc on 10.140.0.90:53: no such host'
  2021-01-07T16:30:59Z Failed to dial backend: 'dial tcp: lookup kubernetes.default.svc on 10.140.0.90:53: no such host'
  

• In the SDN Pods, the following error messages are visible and Pods may appear stuck in the ContainerCreating phase:

  Error executing ovs-ofctl: ovs-ofctl: -:2: 0/0: invalid IP address
  

• The issue only appears on OpenShift Container Platform clusters that are using NetworkPolicies.