Logout with "Not Permitted" Message

System is logging me out during my activity on the screen with a message Not Permitted. It may be noted that this happens as Administrator and other users. I am using version 13.x.x.

It does if you have another instance running on same server having similar ip. In user settings change simultaneous login to 2 or more.

Thanks @Muzzy, it works.
However, this is logical for multiple login, but not for multiple instance on different port.