If you are able to connect to 3-Series processors and other Crestron devices via USB or Ethernet, but you are only able to connect to 4-Series processors via Ethernet and cannot discover or connect via USB, then there may be an issue with the Crestron drivers used to connect to 4-Series devices. Prior to doing anything with drivers, first uninstall Crestron Toolbox and attempt a clean re-installation using the Crestron MasterInstaller.

If you are still unable to connect to 4-Series processors via USB after re-installing Toolbox and verifying it is up-to-date

1. Disconnect your computer from the 4-Series processor and unplug the USB
2. Close any Crestron applications that are running
3. Open Device Manager by either pressing Win+R and typing 'devmgmt.msc' into the search bar, or by pressing Win+S and searching for 'device manager'
4. Right-click 'View > Show hidden devices'
5. Under 'Network adapters', look for a device called 'Remote NDIS6 based Device'
6. Right click the device and navigate to the 'Driver' tab
7. Verify that 'Crestron Electronics Inc.' is the Digital Signer
8. Click 'Uninstall Device'
9. Repeat steps 4 through 7 for any other 'Remote NDIS6 based Device' that are still listed under 'Network adapters'
10. Reboot your computer
11. The next time you connect to the 4-Series processor, the drivers should be automatically reinstalled and the device should be able to be discovered and connected to via USB