More customers are requesting or specifying BACnet Secure Connect. While adoption has been very slow, the protocol appears to have reached a point of maturity as most of the major BMS/DDC manufacturers now support SC: https://www.bacnetinternational.net/btl/index.php?pr=32

"BACnet/SC, defined in Addendum 135-2016 bj, uses WebSockets and TLS to implement peer authentication, message encryption, and reliable connection-oriented communication between BACnet/SC devices. BACnet/SC can be implemented on any IPv4 or IPv6 network."