Windows Server allows concurrent administrative sessions by default. You can enable these without any patches through Group Policy: Press Win + R , type gpedit.msc , and hit Enter.
The for Windows Server 2012 R2 is a common community-driven solution used to bypass the default limit of two concurrent Remote Desktop (RDP) sessions. While Windows Server editions naturally support multi-session environments, they typically require a properly configured Remote Desktop Session Host (RDSH) role and paid Client Access Licenses (CALs) to exceed two simultaneous connections. Understanding the Termsrv.dll File universal termsrv.dll patch windows server 2012 r2