ssh authentication issues

Roughly since 2016 jul 06 I experience more and more common authentication issues when trying to connect to bitbucket server over ssh.

The problem is that the server closes the connection without any notice when my private key is offered. When retrying on the same server I randomly succeed or fail

Maybe it's important, that I'm using an Aladdin eToken to store and sign requests with an RSA key.

I've attached two ssh logs one with the error another with a success. For the logging I've used an ip address to be sure I connect to the same ip, but I can reproduce the error on any of the public ips.