Windows Server 2016 – WFP callout driver blocks RPC and domain traffic – Fix and Prevention

📖 ~1 min read

Table of contents

1. Symptom & Impact
2. Environment & Reproduction
3. Root Cause Analysis
4. Quick Triage
5. Step-by-Step Diagnosis
6. Solution — Primary Fix
7. Solution — Alternative Approaches
8. Verification & Acceptance Criteria
9. Rollback Plan
10. Prevention & Hardening
11. Related Errors & Cross-Refs
12. References & Further Reading

Symptom & Impact

Domain join/GPO/RPC operations fail intermittently.

Environment & Reproduction

Appears after callout driver/policy updates.

netsh wfp show state

Root Cause Analysis

Classification logic denies valid RPC traffic.

Quick Triage

Identify denied ports and policy source.

Step-by-Step Diagnosis

Trace WFP layers and deny rule context.

Solution — Primary Fix

Deploy corrected callout and whitelist required RPC paths.

netsh advfirewall firewall add rule name="Allow RPC Endpoint Mapper" dir=in action=allow protocol=TCP localport=135

Solution — Alternative Approaches

Use reduced enforcement mode during maintenance.

Verification & Acceptance Criteria

RPC-dependent workflows complete successfully.

Rollback Plan

Restore prior callout package and firewall policy backup.

Prevention & Hardening

Run policy simulation before production rollout.

Related Errors & Cross-Refs

Related to NDIS filter drops and AD connectivity issues.

Related tutorial: View the step-by-step tutorial for Windows Server 2016.

View all Windows Server 2016 tutorials on the Tutorials Hub →

Browse all common problems & solutions on the Tutorials Hub.

References & Further Reading

WFP and RPC networking references.