It was working for long time and suddenly it stopped accepting multiple users. I'm not sure how to debug the issue. termsrv.dll version is 6.1.7601.24234 and it is as same as another VM which is 2008 R2 and it has no issues with multiple users.
There was no windows updates or GPO updates. Any suggestions on how to troubleshoot it? Nothing in the even viewer related to this.
Are there any tools to check which terminal server it is pointing to?