Notification error in Job server

Hi Experts,

Our team is using Desginer through VM. Issue is that some developers in team is getting notification error while login to desginer while others are not. All of us are  using same terminal server to connect in.We have tried changing the port in Options(Unchecked the job server options and provided 3500-3600). But with same settings it works for some but not others!!!.

As we have notification error ,when we try to execute job it is showng 'Job server selected is not working'.

Please help.

Thanks,
Ancy