Just wanted to share with you how I did that:
In your DT home directory, edit both dtfrontendserver.ini and dtserver.ini file with the following setting:
which will disable both TLSv1 and TLSv1.1, and only allow TLSv2. You can run a test:
openssl s_client -connect server_name:9911 -tls1_1
which will tell you TLSv1.1 is disabled.