Adding First Server or additional Server to a Database Aavailability Group Fail with error message. 
"A Server Side database availability group Administrative Operation failed. Error the Operation faield with message: Error 0x6f7 (The Stub Received Bad Data)

Casue:
 
Cluster creating process calls WMI to add a node to cluster and checks for all the valid IP Addresses on Network Process and errors when invalid entry is found On network card. 

a search for IP Addresses :  __in string IPAddresses[],      : IP addresses of the cluster.

If Network Cards are found with out DefaultGateway onthe node, following error is logged in DAG Task logs.

Connecting to server 'Server.Contoso.com' via WMI...
[Fetching the network adapters and ignoring the ones without default gateways.
Server.contoso.com has an address: 192.168.10.2/24 default gateway(s)=====<none> [invalid] ---Private network
Server.Contoso.com has an address: 10.0.1.15/24 default gateway(s)=======<none> [invalid] ---Public network
How to fix :
 
Add Default Gateway on  Network Cards which are part of Cluster.
 
More Information :
 
Check for following error message in DAG Task logs
 
Following Error is logged in DAG Tasks Log

The operation wasn't successful because an error was encountered. You may find more details in log file "C:\ExchangeSetupLogs\DagTasks\dagtask_XXXX-XX-XX_XX-XX-XX.XXX_add-databaseavailabiltygroupserver.log".
 WriteError! Exception = Microsoft.Exchange.Cluster.Replay.DagTaskOperationFailedException: A server-side database availability group administrative operation failed. Error: The operation failed with message: Error 0x6f7 (The stub received bad data) from cli_RpccCreateCluster ---> Microsoft.Exchange.Rpc.RpcException: Error 0x6f7 (The stub received bad data) from cli_RpccCreateCluster
   at ThrowRpcException(Int32 rpcStatus, String message)
   at Microsoft.Exchange.Rpc.RpcClientBase.ThrowRpcException(Int32 rpcStatus, String routineName)
   at Microsoft.Exchange.Rpc.Cluster.ReplayRpcClient.RpccCreateCluster(String clusterName, String firstNodeName, String[] ipAddresses, UInt32[] rgNetMasks, String& verboseLog)
   at Microsoft.Exchange.Cluster.Replay.ReplayRpcClientWrapper.<>c__DisplayClass1e.<RunCreateCluster>b__1c()
   at Microsoft.Exchange.Cluster.Replay.ReplayRpcClientWrapper.<>c__DisplayClass32.<RunRpcOperationDbName>b__30()
   at Microsoft.Exchange.Data.Storage.Cluster.HaRpcExceptionWrapperBase`2.ClientRetryableOperation(String serverName, RpcClientOperation rpcOperation)
   --- End of inner exception stack trace ---