We are trying to connect from an application installed on a virtual machine to a database as part of an AWS RDS in the cloud.
There are several routers and firewalls between the source and the target system and there is also NATting happening of the source IP.
A connection test in PowerShell works.
However, when trying to connect to the database with a connection string from within the application, a TDS pre-login handshake error message appears.
A traffic capture with Wireshark also did not provide a clear solution to the error.
We have also tested the connection to the database from SSMS (SQL Server Management Studio) and the same error message appears.
When testing the connection from a different virtual machine the problem does not occur.
So it is not due to a specific application.
My guess is that somehow the SQL Server can't understand the pre-login message and kills the connection.
Does anybody know how to analze this pre-login message in Wireshark to derive further possible solutions?
We turned off the encryption on the AWS RDS but this did not help.
This is the Wireshark capture:
