Cannot add client. No Contact Address. (4033318)

Cannot add client. No Contact Address.

After successful installation of an NVBU client, it is impossible to add the client to the NVBU server.
The following steps have been verified and all setup correctly:
- NVBU service is running
- no firewall exit between NVBU server and client
- ping, telnet and forward/reverse dns lookups all work fine both ways

In NVBU Client Management the following error pop up message is returned:
"Netvault must be active before the client may be added."

Trace shows that the Network Manager process fails to connect to the client:

------------
Error 4 getting TCP message, mark socket down
Lost connection connecting to 'xyz', state 0 Disconnect TRUE
No contact address for 'xyz'
------------

The netvault/etc/machines.dat file on the NVBU server does have an entry for the client but is missing a "Contact Address" which other added clients have.
.

All NetVault clients and servers are designed to brodcast UDP availability packets on their network segments, this is how each NVBU machine knows about the other
and provides information on how to contact each other.
The machines.dat file on each NetVault server is the file that receives all the packets from all clients and displays their contact information.
The condition for adding a client to a server is that the UDP packet received from the client has a "Contact Address", without this variable, it is impossible to add a client.
It looks like on certain machines there is an issue providing the contact address during packet formation.
This is more than often an issue on the machine's network stack and not a NVBU problem.

For more information on this topic, please see the Administration Module 1 Introduction to NetVault Backup-Web-based Training

To workaround the missing "Contact Address" here is how to provide that information manually:

- On the client make sure it stops Broadcasting availability packets
nvconfigurator > Network Manager > Connections > uncheck "Boradcast details to machines on local networks"> Apply and restart NVBU to apply the configuration.

- On the NVBU server edit the "..netvault/etc/machines.dat" file and manually add the "Contact Address =<IP_adress>"
Since the client no longer broadcasts information the enrty for this client in the server's machines.dat will not be overwritten everytime we search for the client.

- Now edit "..netvault/config/clientlist.txt" on the NVBU server and add the client at the end of the list respecting one client per line and exact syntax used to name
the NetVault client during NVBU installation

- Restart NVBU on the server and you will see that the client will already be added on the list of "Clients" under Client Management

- Now right click the client and select "Check Access", by doing so, the NVBU server's Network Manager process will use the machines.dat information we entered manually
to check whether there are any NetVault processes behind the provided contact address and will find the client.

- Note that if a password was configured during the client installation, you will be prompted to enter it.

Important:
Since we have disabled the ability to broadcast information on the client, remember that if you perfom any changes on this client's hostname/IP,
these will not be propagated to the server which will always use the stored information to contact it.
So it is important that if any changes happen to networking on the client, you repeat the above manual steps to be able to contact it under the new information.