Verify wbemtest (from the DGE/x) is able to connect and issue queries to the remote host in question
If wbemtest is able to successfully connect to the remote host and issue queries, please open a support ticket so that we may be able to assist further
If wbemtest encounters "RPC Server Unavailable" please see the following article for items to review: https://social.technet.microsoft.com/wiki/contents/articles/4494.windows-server-troubleshooting-the-rpc-server-is-unavailable.aspx#RPC_Quick_Fixes
The WBEMTest should also return an ERROR code '0x123456', googling the error code will give you even more detail on the exact cause.
e.g. ‘RPC server unavailable’ 0x800706BA https://enterpriseit.co/windows-server/rpc-server-unavailable-0x800706ba/