How to move FTP folder (wnos.ini) to another server

Hi guys,

I have a very old system of Wyse Dx0D and Rx0L Thin Clients.  They are old but they work (mostly).  We use a wnos.ini file to specify all of the connection information to our RDS2012 farm and we set a background image etc.  The server that holds the wyse\wnos\ file structure is being turned off so I need to tell our thin clients to look elsewhere for it's configuration.  

We have Scope Option 161 setup on our DHCP server that have a value of 'old server name'.  Nothing else to do with thin clients is set there, and on the C:\ of old server I have this folder structure C:\FTP Site\wyse\wnos

I have copied the folder FTP Site and placed it on the C:\ of another server.  Changed the 161 DHCP option to be the name of the new server (I have tried the IP as well).

Thin Clients know something has changed as now when I boot them up it goes through the normal steps of:

Looking up IP Address for DHCP
Looking up WDM by DHCP inform
Contacting File Server

But when it boots, no domain set and no background picture and you can't logon to the network.  

I have googled extensively, but all it says in order to change the FTP server is to change the DHCP option 161 and copy the folders over.  

Any help would be enormously appreciated!

Many thanks,

Paula