Welcome to this community!!
This is a known issue with VDR 1.x. VDR wont be accessible from VC after VC restarts.
To workaround this issue:
1.Connect directly to the ESX host on which VDR is located using the vSphere Client.
2.Go to the home page of the ESX host.
3.Under Solutions and Applications, click VMware Data Recovery.
4.Type the IP address or hostname and then click Connect.
5.After the VDR appliance is connected to the ESX host, go to vCenter Server and try connecting to VDR.