SSH Tunneling - Timed out while waiting for handshake


We are using an ssh tunnel on kubernetes to connect to our RDS on a private network.
I downloaded the public key from the retool site, and opened in the RDS security groups the white lists of:

In the tunneling pod logs we can see this errors:

Server listening on port 2222.
Server listening on :: port 2222.

When we try to connect to the RDS using ssh bastion configuration from retool, we get this message:

Test connection failed
Timed out while waiting for handshake

Initially, we suspected that the SSH might not be working correctly, or perhaps the tunneling port (2222) is being denied. To troubleshoot, we rebuilt the tunneling image with our public key (not Retool's), and then attempted to access the RDS using SSH tunneling from another client. It worked successfully, confirming that the SSH tunneling itself is functioning (even with the error log i mention in the pod log)

Next, we considered the possibility of connection issues between the SSH tunneling pod and the RDS. To investigate, we installed the MySQL client and attempted to access the RDS from the pod itself. This test was successful, indicating that the connection between the pod and the RDS is fine.

What could be the problem preventing Retool from connecting to our RDS?

Thanks in advanced,