Do you have a proxy setup in the Robot machine? (Start → Internet Options → Connections → LAN Settings)
Which is the robot version?
Are you having an On-Premise Orchestrator?
Does your robot have Packages View and Libraries View privileges in your Orchestrator?
Which is the robot type on the impacted machine (User mode or Service Mode)?
You may try to rename the packages folder to packages_backup in the C:\Users\username.nuget\packages and then retry to run the process from Orchestrator