"Error validating device name" means that the device is unable to connect to the Wasp MobileAsset Windows Service, which is the component the validates the device name.
 
This is a connectivity problem, not a problem with the device name. Troubleshoot the network connection between the device and the Service PC.
 
MobileAsset v7: mobile device connection troubleshooting:
https://support.waspbarcode.com/kb/articles/1061
 
HC1 & WPA1000-II: Network configuration to enable name resolution and/or internet browsing:
https://support.waspbarcode.com/kb/articles/1018
 
WDT60: Network configuration to enable name resolution and/or internet browsing:
https://support.waspbarcode.com/kb/articles/1099
 
Windows Mobile Device Center settings interfere with mobile device's connection to Wasp service:
https://support.waspbarcode.com/kb/articles/1101
 
Summit Client Utility: How to set up wireless, and choose from multiple SSIDs (wireless networks):
https://support.waspbarcode.com/kb/articles/1037