title: How to FIX AWS DMS to RDS connection Error?
body: <p>I'm having a tough time connecting DMS instances to RDS instances and need some help.</p>
  
  <p><strong>Situation:</strong>
  I've created Postgres and SQLServer RDS instances both with public access using the same (default) VPC and no SSL. I've added VPC inbound firewall rules opening the RDS instances my external and DMS instance IP addresses. Inbound rules and user/pw to the database have been verified from desktop apps on at my remote site.</p>
  
  <p>I've also created DMS source endpoints to my remote IP address. Endpoint tests verify "passed" connection.</p>
  
  <p><strong>My Problem:</strong>
  The Target endpoints from DMS to RDS fail connection validation. I was assuming creating DMS and RDS instances using the same VPC would guarantee connection between them. I was also assuming adding inbound rules to open ports between DMS and RDS instances would also work, yet connection between them fail.</p>
  
  <p>ERROR: <code>RetCode: SQL_ERROR SqlState: 08001 NativeError: 101 Message: [unixODBC]timeout expired [122502] ODBC general error.]</code></p>
  
  <p>What am I doing wrong ?</p>
  
  <p><strong>Update:</strong> If I create a DMS instance without a public IP address, the target connection passes validation. It worked once</p>
  
  <p><strong>Update 2:</strong> If I open up the inbound to allow all IP addresses, the connection between the instances succeed. </p>
  
  <p>It is looking like a network issue. But why doesn't placing the DMS instance IP address into the firewall permit connections ?  </p>
  
  <p>tia</p>