I would certainly be trying an updated WMS as 3.0 was released in 2020 and is no longer supported.

When I see this happen it boils down to a few things. 

1.  Can the device (thin client) resolve both the Netbios and FQDN of the WMS Server?
   1. Try to ping server and server.domainname.com from the command prompt
2. Is the windows firewall enabled on the WMS server possibly blocking 443 or 1883?
3. When the device is registered to WMS, can you right-click on it and "Send Message", does it pop up on the client?
4. Can you share screenshots of the error?
5. Does the device reflect an image request has been received and do you reboot it?  
6. Does it fail in Merlin/

Hello,

I'm sorry, I come back to this issue.

I can resolve the FQDN of the WMS server, I can ping too

I deactivated the Windows firewall on the WMS server, I can see the https traffic and also traffic on 1883 

A message sending from WMS server is well received on the client

No Merlin error (version 4.1)

Screenshot :

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ERROR WMS File Repository Server not found. Error code : 105)

Error stage : Repository validation.

Reason : Could not connect to repository server

Solution : Check the network connection/authentication.

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I reinstalled it from Dell USB