Starting on January 31st, 2021 Robin will be removing support for TLS 1.1 connections to its servers for a more secure form of communication.
Who’s affected: Exchange customers that do not have their servers configured for TLS 1.2.
What’s affected: Realtime calendar syncing is not possible without TLS 1.2 communication to our servers.
Instructions: Follow the two-part guideline from Microsoft to ensure your servers are up to date and configured to use TLS 1.2:
After you've completed the above instructions and have verified TLS 1.2 outbound connections, calendars should sync as normal.