Hi @ian2x4b523p ,
The issue you're encountering "A network-related or instance-specific error occurred while establishing a connection to SQL Server" strongly suggests that outbound port 1433 is blocked on the VM hosting your on-premises data gateway. This port is required for connecting to the Fabric SQL endpoint, and blocking it would prevent the gateway from successfully establishing a SQL connection.
For the on-premises data gateway to function correctly, it must be able to communicate outbound to Azure Relay and other supporting Azure services. The required outbound ports for this communication are:
TCP 443
TCP 5671–5672
TCP 9350–9354
These ports are essential regardless of your data destination, as they support secure, relay-based communication from your on-premises environment to Azure. It's important to note that no inbound ports need to be opened for the gateway itself.
Reference: Adjust communication settings for the on-premises data gateway | Microsoft Learn
In addition, Fabric workloads such as pipelines and dataflows require outbound connectivity to various cloud services, particularly for accessing staging storage and executing copy operations. If you're copying data directly to a Fabric SQL endpoint, outbound connectivity over port 1433 is also required. Specifically:
TCP port 443 must be open to:
*.core.windows.net – for access to Azure Data Lake
*.frontend.clouddatahub.net – for pipeline execution within Microsoft Fabric
TCP port 1433 must be open to:
*.dfs.fabric.microsoft.com
*.datawarehouse.pbidedicated.windows.net
*.datawarehouse.fabric.microsoft.com
These domains represent Fabric’s data warehouse and lakehouse services, which use the Tabular Data Stream (TDS) protocol over port 1433—standard for SQL-based connections.
Given your symptoms and the type of error message you're receiving, it is highly likely that port 1433 is being blocked by your firewall or network configuration. You should confirm that this port is open for outbound traffic from your gateway VM to the relevant Fabric SQL endpoints.
Although your network ports test on the gateway application has passed, it's worth noting that this test often verifies only the basic connectivity required for the gateway service itself (e.g., Azure Relay), not necessarily connectivity to Fabric SQL endpoints.
Therefore, to resolve the issue ensure that port 1433 is open outbound from your gateway VM.
Verify that all required gateway communication ports (443, 5671–5672, 9350–9354) are also open though your test results suggest these may already be properly configured.
If your environment cannot support domain-based allow lists (i.e., wildcard FQDNs), a broader rule to allow outbound TCP 1433 to all destinations (0.0.0.0/0) may be necessary, especially in restrictive environments.
By adjusting your firewall or proxy settings to accommodate these requirements, you should be able to eliminate the SQL connectivity error and enable successful data movement from your on-premises SQL Server to the Fabric SQL database.
Hope this helps.
Thank you.
