1. Ensure that the Applications Manager installed server has internet connectivity. The following hosts must be accessible from the APM server. 
   

Hosts (Azure Global)

1. login.microsoftonline.com - Used for Authentication in all the services
   
2. management.azure.com - Used for Data Collection in all the services
   
3. <storage-account>.table.core.windows.net - Used to fetch Diagnostic Extension metrics from the Azure Virtual Machine
   
4. Azure SQL DB Server Name - Used to establish a JDBC connection to fetch query metrics (For example, the JDBC Url would be: jdbc:sqlserver://<DBserver>.database.windows.net:1433)
   

Hosts (Azure Gov Cloud)

5. login.microsoftonline.us - Used for Authentication in all the services
   
6. management.usgovcloudapi.net - Used for Data Collection in all the services
   
7. <storage-account>.table.core.usgovcloudapi.net - Used to fetch Diagnostic Extension metrics from the Azure Virtual Machine
   
8. Azure SQL DB Server Name - Used to establish a JDBC connection to fetch query metrics (For example, the JDBC Url would be: jdbc:sqlserver://<DBserver>.database.usgovcloudapi.net:1433)
   

Hosts (Azure China)

9. login.partner.microsoftonline.cn - Used for Authentication in all the services
   
10. management.chinacloudapi.cn - Used for Data Collection in all the services
    
11. <storage-account>.table.core.chinacloudapi.cn - Used to fetch Diagnostic Extension metrics from the Azure Virtual Machine
    
12. Azure SQL DB Server Name - Used to establish a JDBC connection to fetch query metrics (For example, the JDBC Url would be: jdbc:sqlserver://<DBserver>.database.chinacloudapi.cn:1433)
    

1. If your setup uses a proxy, ensure it is properly configured in APM. If proxy exclusions are required, add the above-mentioned hosts to the proxy settings.
   
2. Utilize the URL Debug Tool to verify if you can connect to the specified hosts.
   
3. If the issue occurs intermittently, configure a URL monitor within Applications Manager to track and monitor any potential downtime.