Dell 5480 USB not working with WD15 & Citrix Receiver

That's a known issue on the TB16 dock due to the ASMedia USB driver that it requires to be installed. That driver is not required for the WD15 docks, but if you installed that driver anyway on those systems, it might affect them as well.  The fix is simply to update Citrix Receiver on the affected systems to at least 4.9.  This Dell support article explains the issue and provides a link to Citrix to download an updated Citrix Receiver client: www.dell.com/.../tb16-dock-losing-connection-to-peripherals-and-network-on-reboot-with-citrix-receiver-client-software-installed

We are allready using the Citrix receiver version  4.9, and have used all the latests dell firmware and drivers

Looks like some driver error with Dell and Citrix, when i am using a local admin users the problem is NOT there, but if i am using a regular user(NOT local admin) the problem is there

Interesting find!  I remember tearing my hair out trying to figure out why iTunes would always lock up within about 30 seconds when launched normally but ran perfectly fine when launched with elevated privileges, even after a clean rebuild of the system.  It turned out it was conflicting with the Bluetooth tray icon application, of all things!  Most drivers themselves will load identically between admin and standard users because most operate in "kernel mode", but now that you've identified this distinction, I would start by going through the Task Manager > Startup tab and seeing if you can find something that allows the dock to work properly when disabled.