If you encounter Proxy Authentication Error 2606 in OneDrive, follow the solutions below. The Proxy Authentication error can result from a network glitch. We should ...

Can't you add machine accounts to the autheticated users on the ISA server? Or better yet, use Domain Computers group. That would allow access for all system accounts on all computers.

Learn how IP lookup, reputation checks, VPN detection, and risk-based MFA strengthen enterprise authentication and prevent fraud.