When you see an instant "complete" but no file, it means NPS asked the server for the URL, got a 404 Not Found or a 302 redirect to a login page, and gracefully crashed. The client doesn't know how to tell you "That link is dead" because the code assumes the mirror is always alive.
Add the entire NPS folder to your AV exclusion list. Then add your Downloads folder to exclusions. Reboot. The Golden Rule of NPS If the download finishes in under 5 seconds, it didn't happen. nopaystation not downloading pkg
NPS is a museum curator, not a store. It points to dusty shelves on the internet. When a shelf collapses (link dies), the curator just shrugs and closes the door. When you see an instant "complete" but no