OneDrive desktop client continues to experience authentication problems

The corporate-network versus hotspot result is your strongest diagnostic clue: the same desktop client can authenticate and sync elsewhere, so another reinstall is unlikely to isolate the problem. Browser access succeeding does not rule out a network issue affecting the desktop client's authentication or service endpoints. Reproduce one failure and one success with the same user and device, recording both timestamps. Have the identity administrator compare Entra sign-in results, target resources, client details, source IP addresses, and Conditional Access outcomes. In parallel, ask the network team to compare proxy configuration, DNS resolution, TLS inspection, and access to Microsoft's current Microsoft 365 endpoints. Do not assume that no intentional firewall change means the entire path is unchanged. If needed, test a narrowly scoped, administrator-approved network exception rather than disabling inspection company-wide. Continue using the working web client while the teams review redacted logs and network evidence.