We've been monitoring usage of older protocols (TLS v1.0/v1.1), and while most sites have little to no problematic traffic, on some sites we still see significant traffic that would be blocked. To try and make this transition as painless for you as possible, we've decided to postpone the requirement of TLSv1.2.
The new target date for the change is Tuesday, April 2nd.
As of January 23rd, 2019 we will only be supporting connections using TLSv1.2 to connect to Shotgun. Older implementations of TLS (v1.0 and v1.1) have known vulnerabilities that make them no longer secure enough given modern standards and as a result Shotgun's support for these older TLS implementations is being discontinued.