RHUI 環境で、2017年4月1日ごろから、Red Hat コンテンツサーバー(CDN) と RHUA との同期に失敗します。

Issue

RHUI環境において、2017年4月1日ごろから、Red Hat コンテンツサーバー(CDN) と RHUA との間において以下のエラーで同期に失敗しています。

なぜ、同期に失敗していますか？
どのようにすれば問題を解決することができますか？

rhui-manager コマンドによるステータス確認の結果

# rhui-manager --server $(hostname -f) status
server-abc01.cloud_xxxx.xxx.com .................... [  UP  ]
server-abc01.cloud_xxxx.xxx.com .................... [  SUCCESS  ]
server-abc02.cloud_xxxx.xxxcom.................... [  UP  ]
server-abc02.cloud_xxxx.xxx.com.................... [  SUCCESS  ]

Red Hat Software Collections for RHEL Server from RHUI (RPMs) (6Server-i386)  [  ERROR  ]

Red Hat Update Infrastructure 2 (RPMs) (6Server-x86_64) ............... [  ERROR  ]

Red Hat Enterprise Linux 6 Server - Optional from RHUI (RPMs) (6Server-i386)  [  ERROR  ]

Red Hat Enterprise Linux 6 Server - Optional from RHUI (RPMs) (6Server-x86_64)  [  ERROR  ]

Red Hat Enterprise Linux 5 Server from RHUI (RPMs) (5Server-i386) ..... [  ERROR  ]

Red Hat Enterprise Linux 5 Server from RHUI (RPMs) (5Server-x86_64) ... [  ERROR  ]

Red Hat Enterprise Linux 6 Server from RHUI (RPMs) (6Server-x86_64) ... [  ERROR  ]

Red Hat Enterprise Linux 7 Server from RHUI (RPMs) (7Server-x86_64) ... [  ERROR  ]

Red Hat Software Collections RPMs for Red Hat Enterprise Linux 7 Server from RHUI (7Server-x86_64)  [  ERROR  ]

Red Hat Enterprise Linux 7 Server - Optional from RHUI (RPMs) (7Server-x86_64)  [  ERROR  ]

Red Hat Software Collections for RHEL Server from RHUI (RPMs) (6Server-x86_64)  [  ERROR  ]

Red Hat Enterprise Linux 6 Server from RHUI (RPMs) (6Server-i386) ..... [  ERROR  ]

Identity certificate expiration date = 2024-11-30T16:03:20Z  .......... [  OK  ]

Entitlement CA certificate expiration date = 2024-11-30T12:42:43Z  .... [  OK  ]

/var/log/pulp/grinder.log より

2017-03-31 05:00:32,033 9333:2220698202333: grinder.YumInfo:ERROR: activeobject:160 Caught exception when trying to fetch metadata file primary from [https://cdn.redhat.com//content/dist/rhel/rhui/server/7/7Server/x86_64/os]: failure: repodata/11135097f3b05c12346fc83d55555555555-primary.xml.gz from : [Errno 256] No more mirrors to try.
2017-03-31 05:00:32,033 9333:2220698202333: grinder.Retry:ERROR: activeobject:160 Attempt 1: Caught exception: failure: repodata/11135097f3b05c12346fc83d55555555555-primary.xml.gz from : [Errno 256] No more mirrors to try.. Will retry in 5 seconds.