Hyper-V manager asking password to connect to VM after adding FQDN

Hi,

I`ve windows 2012 server with Hyper-V server installed. It is in workgroup and I added FQDN from registry because I didn`t want to restart it. The replication works perfectly well but when I try to connect to VM from hyper manager, it says"The logon attempt failed" it asks for password.(User name, password and domain:blank).

I tried local and domain passwords but always says incorrect. I can access via RDP without any problem. I need to restart the Server and I`m scared I won`t be able to run the VMs again.

Thanks for your help in advance.