Power Bi Report Server access from outside stuck on loading data

Hi MarieKAA 

Your issue with Power BI Report Server (PBIRS) reports getting stuck on "Loading data" when accessed externally could be related to authentication, network configuration, or browser security settings. Since you can successfully access the /reports page, log in, and view the report list, but the reports themselves fail to load without errors, this suggests that the problem might be due to authentication mismatches or blocked service requests when rendering reports.

The 401 warning in the RSPortal log ("Received a request with an unmatched or no authentication scheme") indicates that external requests might not be passing authentication properly to PBIRS. This often happens when Kerberos delegation is not correctly configured, or when Windows Authentication (NTLM/Kerberos) is required, but the request from external networks does not pass credentials correctly. You can try enabling Anonymous Authentication temporarily in Reporting Services Configuration Manager under Web Service URL settings to see if it helps.

Another possible cause is CORS (Cross-Origin Resource Sharing) or SameSite cookie policies in modern browsers. If authentication is handled via Integrated Windows Authentication (IWA), browsers like Chrome and Edge block third-party cookies, preventing proper authentication flow. You can test this by disabling "SameSite by default cookies" in Chrome ( chrome://flags/#same-site-by-default-cookies or manually allowing the PBIRS domain in site settings.

Additionally, since your issue persists after upgrading to PBIRS January 2025, check if firewall rules or reverse proxy settings (if applicable) are blocking WebSocket or API calls required for loading data externally. Running F12 Developer Tools (Network tab) while accessing the report externally can help identify blocked requests or failed authentication challenges. If PBIRS is behind a load balancer or proxy, ensure that it correctly forwards Windows Authentication headers to PBIRS.

You might also want to check service account permissions for PBIRS and ensure that your account has proper access by adding it explicitly in the PBIRS Security settings (even though you're an admin). If possible, try enabling Forms Authentication instead of Windows Authentication for external access to see if that resolves the issue.