Curl error 28

Hi
With yum update command, I have the messages:
Red Hat Enterprise Linux 8 Server - Extras (RPM 0.0 B/s | 0 B 02:00
Errors during downloading metadata for repository 'rhel-8-for-x86_64-appstreampms':
- Curl error (28): Timeout was reached for http://172.27.157.1:81/content/di/rhel8/8Server/x86_64/appstream/os/repodata/repomd.xml [Connection timed out aer 30001 milliseconds]
- Curl error (28): Timeout was reached for http://172.27.157.1:81/content/di/rhel8/8Server/x86_64/appstream/os/repodata/repomd.xml [Connection timed out aer 30000 milliseconds]
Error: Failed to download metadata for repo 'rhel-8-for-x86_64-appstream-rpms'Cannot download repomd.xml: Cannot download repodata/repomd.xml: All mirrors we tried
Any idea?
best regards