Don’t get lost down this rabbit hole : https://support.citrix.com/article/CTX207466/error-errsslversionorciphermismatch-when-connecting-to-netscaler-gateway-using-chrome

To disable TLS 1.0 and TLS 1.1 on NSIP by using the GUI

1. Navigate to Traffic Management > Load Balancing > Services.

2. On the Services page, click the Internal Services tab, select the check box next to the internal service for NSIP to be edited, and click Edit.

   Note: There might be different services for NSIP for different secure ports. Make the required changes on all the applicable ports individually.

3. Click the pencil icon under SSL Parameters section to disable the required TLS.

4. Finally click OK and click Done.