about endpoint connection

Question

We have created a VPC to connect to the on prime database using AWS DMS. I am able to ping the on prime database server
and connect my mssql database using Azure data studio from the VPC but my DMS is not able to connect to my mssql 
database on private ip.  Except captured while testing the connection in following:
"""Test Endpoint failed: Application-Status: 1020912, Application-Message: Failed to connect  Network error has occurred, Application-Detailed-Message: RetCode: SQL_ERROR  SqlState: HYT00 NativeError: 0 Message: [unixODBC][Microsoft][ODBC Driver 17 for SQL Server]Login timeout expired"""

Answer

Hello

Seems like your On-premise SQL Server is not allowing connections from DMS Replication Instance(RI). Please consider the below troubleshooting steps to fix the connectivity issue.

1) Check if the route table, NACL, Security Groups of DMS RI are same as like the instance which you had no issues in connecting to the On-prem SQL Server from Azure Data studio.

2) Make sure that RI IP Address is added in the On-prem network to allow the inbound connections for SQL Server from the VPC where DMS RI is associated.

3) Verify if the outbound rules of RI are allowed to communicate with On-prem network. Outbound rules for RI is most important in establishing communication with source and target endpoints.

Further I would recommend going through the below Knowledge center article that helps you in troubleshooting DMS endpoint connectivity issues.

https://aws.amazon.com/premiumsupport/knowledge-center/dms-endpoint-connectivity-failures/

about endpoint connection

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