Remote app cannot launch

Hi,

1. I have been setup RDS using 3 servers ( RDCB, RDSH and RDWA). When access remote app i got error as below :

"The remote computer could not be found. Please contact your helpdesk about this error"

2. If client pc joint domain, the remote app can run ok.

3. Is there a possible way to run remote app without join domain?

4. Can remoteapp be launched from non AD pc in the network?

Thanks