システム登録が "HTTPConnectionPool(host='169.xxx.xxx.xxx', port=80): Read timed out. (read timeout=10.0)" というエラーで失敗する

Issue

• Microsoft Hyper-V ホスト上で実行されている仮想マシンのシステム登録が以下のエラーで失敗します。

  # subscription-manager register
  Registering to: subscription.rhsm.redhat.com:443/subscription
  Username: <login-id>
  Password: 
  Network error, unable to connect to server. Please see /var/log/rhsm/rhsm.log for more information.
  

  # cat /var/log/rhsm/rhsm.log
  2022-04-20 13:18:43,237 [ERROR] subscription-manager:9123:MainThread @managercli.py:218 - Error during registration: HTTPConnectionPool(host='169.xxx.xxx.xxx', port=80): Read timed out. (read timeout=10.0)
  2022-04-20 13:18:43,237 [ERROR] subscription-manager:9123:MainThread @managercli.py:219 - HTTPConnectionPool(host='169.xxx.xxx.xxx', port=80): Read timed out. (read timeout=10.0)