Possible causes and solution(s)
Only if you are using BIS with an older version than 4.9.1 in conjunction with a Connection Server (OPC server is running on a different computer than Login Server)
With beginning of January 2022 Microsoft plans to roll out an update with a possible impact on BIS Connection Servers at all older BIS versions:
KB5004442—Manage changes for Windows DCOM Server Security Feature Bypass (CVE-2021-26414) (microsoft...
Beginning with BIS 4.9.1 we changed the COM standard security settings to the values shown in the screenshot.
If you are using BIS with a Connection Server before version 4.9.1, these changes must be implemented manually before installing the security update from Microsoft.