How to Fix Proxy Authentication Error 2606 (Easy Guide)

Proxy Authentication Error 2606 appears when Windows apps like OneDrive or Outlook fail to authenticate through a proxy. It usually points to misconfigured proxy/VPN settings, residual Internet Options (IE) settings, or restrictive network policies.

What Is Proxy Authentication Error 2606?

The message typically reads along the lines of “Please check your proxy configuration and try again [2606].” In practice, the client cannot complete sign-in or sync because proxy rules, legacy LAN settings, or security tools are blocking or misrouting the authentication flow.

Why It Happens (Common Causes)

Cause	Key Detail
Proxy / VPN misconfiguration	Wrong proxy settings or broken auto-detect disrupt authentication.
Internet Explorer remnants	Legacy LAN/proxy settings still influence Windows auth flows.
Updates / patches issues	Certain OS or security/VPN updates can trigger proxy auth failures.
Registry corruption	Bad values under Internet Settings → Connections block access.
Firewall / policies	Corporate firewalls or forced proxies interfere with sign-in.

If you’ve seen related problems like Proxy Error 400 on Janitor AI, the underlying causes often overlap with proxy misconfigurations and network policy conflicts.

Fixes: Step-by-Step Solutions

Fix 1: Reset Internet Options (Legacy IE) to Defaults

Even if you never use Internet Explorer, Windows still consults its Internet Options for proxy/LAN settings. Resetting them clears hidden conflicts and stale policies. Similar resets help in cases like Proxy Error 401 on Janitor AI.

1. Press Windows + R, type RunDll32.exe InetCpl.cpl,ResetIEtoDefaults, and press Enter.
2. In the dialog, confirm the reset to restore default Internet Options.
3. Restart the PC and try signing in again.

Fix 2: Disable Proxy or VPN Temporarily

Misapplied proxy rules or a strict VPN can block or loop authentication traffic. Services that fail to respond properly often surface as errors similar to the Proxy Error: No Response from Bot (PSGHAG2).

1. Go to Settings > Network & Internet > Proxy. Turn off Use a proxy server if enabled.
2. Toggle Automatically detect settings off and on once to refresh.
3. Disconnect your VPN and test sign-in or sync again.

Fix 3: Reset the Network Stack (IP/Winsock/DNS)

1. Open Command Prompt as Administrator.
2. Run, one by one:
   netsh int ip reset
   netsh winsock reset
   ipconfig /flushdns
3. Restart the PC and retry the affected app (OneDrive, Outlook, etc.).

Fix 4: Sign Out and Reconnect Your Microsoft/Work Account

1. Sign out of OneDrive/Outlook and your Microsoft account.
2. If applicable, remove stale entries under Settings > Accounts > Access work or school.
3. Restart the device, then sign in again and let policies reapply cleanly.

Fix 5: Repair Internet Settings Registry Values

Corrupted connection blobs can force Windows to reuse bad proxy rules.

1. Open Registry Editor and navigate to:
   HKEY_CURRENT_USER\SOFTWARE\Microsoft\Windows\CurrentVersion\Internet Settings\Connections
2. Delete DefaultConnectionSettings and SavedLegacySettings (they will be recreated).
3. Restart and test again.

Fix 6: Test on a Different Network

This isolates ISP or corporate firewall issues. Connect via a phone hotspot or a different Wi-Fi. If the error disappears, adjust policies on the original network or ask IT to whitelist Microsoft endpoints.

Summary of Steps (Quick Checklist)

Step	Action
1	Reset Internet Options via RunDll32.exe InetCpl.cpl,ResetIEtoDefaults
2	Disable proxy/VPN and retry sign-in
3	Reset Winsock/IP and flush DNS
4	Sign out and reconnect Microsoft/work account
5	Remove corrupted Internet Settings → Connections blobs
6	Test on another network to rule out firewall/policy blocks

Final Thoughts

Most cases of Proxy Authentication Error 2606 come down to stale Internet Options, strict proxy/VPN enforcement, or corrupted network settings. Work through the resets, disable conflicting tools, and verify policies. In managed environments, coordinate with IT to align proxy rules with Microsoft sign-in and sync traffic.

If you run into a different code like a Proxy Error 500, you’re dealing with an internal server fault, not an authentication failure. Use that guide to confirm it’s server-side before you tweak local proxy or VPN settings.

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