Routers Error Code
Systems & Devices
Routers

Error 691 | Access denied

Industry
Systems & Devices
Canonical
/systems/routers/error-codes/error-691/
Last Updated
Feb 27, 2026
Summary

Authentication failed for a PPP connection, often due to credentials or permission.

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What This Code Means

Error 691 commonly indicates a PPP authentication failure. The credentials were not accepted or the connection attempt was not permitted under the current configuration or account state.

Where Users Usually See This Code

  • WAN/PPP connection attempts
  • Device network status dialogs
  • ISP authentication and session setup
  • After modem/router restarts or configuration changes

Why This Code Appears

  • PPP authentication or negotiation failed
  • The WAN link could not be established
  • Name resolution or DHCP assignment failed
  • A modem/router configuration mismatch prevented connectivity

What Typically Happens Next

  • Internet access is unavailable
  • Devices may connect locally but not reach the WAN
  • Retry may succeed after restoring the failing layer

What This Code Is Not

  • It is not always a router hardware defect
  • It is not always caused by the ISP

Troubleshooting Checklist

  • Confirm whether the issue affects one device or the whole network
  • Restart in order: modem (if present) → router → affected device
  • Check WAN status lights and the router status page if available
  • Verify credentials and connection type (e.g., PPPoE) if applicable
  • Test name resolution by trying a different DNS setting if appropriate
  • If the issue persists, contact ISP or router vendor with the full error

Notes And Edge Cases

Some “router” errors are shown by the device OS or connection stack, not the router UI itself.

Related Codes

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