When connecting through web access VDIs assigned using the Device Address client assignment are not correctly allocated and the client device is directed to the incorrect VDI.
This works fine when connecting using AppPortal.
In the vWorkspace console, select Web Access | Your Website | Properties | vWorkspace Connectors (where Your Website is the name of the website that needs to be changed).
Check the box next to "Detect client information before logon":
Click Apply and OK and update the website using either automatic or manual depending on your environment.