How to configure
Navigate to bastion installed installation folder - by default c:\agat\Bastion.
There open the file Open Bastion.XML preferable xml, preferably with notepad++ or other text editing software.
...
Once the ciphers and TLS version are properly configured, save the file and restart the Bastion reverse proxy service and it should be applied.
Cipher Syntax explanation
Putting an exclamation mark ( ! ) before a certain cipher will disable use of that particular cipher.
...
So if the minimum allowed version is tlsv1.2 then there cannot be an allowed cipher which is part of a lower version TLS cipher suite.
Testing
A recommended test would be to use https://www.ssllabs.com/ssltest/ to test the LyncDiscover URL if it is available externally.
...