Diagnose Windows App (Microsoft Remote Desktop / Azure Virtual Desktop / W365 / direct PC) connection issues on macOS. Analyze transport protocol selection (UDP Shortpath vs WebSocket), detect VPN/proxy interference, parse Windows App logs for Shortpath failures, and resolve stuck "Configuring remot

Windows Remote Desktop Connection Doctor Diagnose and fix Windows App (Microsoft Remote Desktop / AVD / WVD / W365 / direct PC) connection issues on macOS, with focus on transport protocol optimization and root cause falsification. Methodology base: the general evidence driven diagnosis discipline lives in the debugging network issues skill. This skill is the Windows App / AVD transport domain layer — it leans toward connection quality optimization more than root cause falsification, so the methodology overlap is lighter. Background Azure Virtual Desktop transport priority: UDP Shortpath TCP WebSocket . UDP Shortpath provides the best experience (lowest latency, supports UDP Multicast). When it fails, the client falls back to WebSocket over TCP 443 through the gateway, adding significant latency overhead. Direct PC connections use plain RDP over TCP 3389 (usually TLS wrapped). They have no Connection Info panel, no gateway reachability tests, and no transport optimization step. For direct PC, the dominant failure modes are: 1. The remote PC is off or unreachable (network/firewall). 2. The Windows App client has a stale or expired Microsoft work/school account that poisons the auth orchestration, leaving the connection stuck at "Configuring remote PC...". 3. The remote PC rebooted (often Windows Update), and the client cannot recover cleanly. This skill handles both scenarios. Diagnostic Workflow Step 1: Determine the Connection Type and Symptom Before collecting evidence, identify which scenario you are diagnosing: Scenario Key Characteristic Primary Evidence Source AVD/WVD/W365 User connects to a cloud desktop through a workspace/gateway Connection Info panel, gateway health checks, UDP Shortpath logs Direct PC User connects to a named PC by hostname or IP (e.g., a home workstation) RDP protocol probe, Windows App log auth chain, Windows side reboot events For AVD/WVD/W365 , ask the user to provide the Connection Info from Windows App (click the signal icon in the toolbar). Key fields to extract: Field What It Tells Transport Protocol Current transport: UDP , UDP Multicast , WebSocket , or TCP Round Trip Time (RTT) End to end latency in ms Available Bandwidth Current bandwidth in Mbps Gateway The AVD gateway hostname and port Service Region Azure region code (e.g., SEAS = South East Asia) If Transport Protocol is UDP or UDP Multicast , the connection is optimal — no further diagnosis needed. If Transport Protocol is WebSocket or TCP , proceed to Step 2. For Direct PC , the Connection Info panel does not exist. Instead, first run the RDP protocol probe in Step 2E to prove the server is reachable, then analyze the Windows App log for auth poisoning or reconnect failures. If the progress dialog is stuck at "Configuring remote PC...", strongly suspect client side identity issues (see Category E). Step 2: Collect Network Evidence Gather evidence in parallel — do NOT make assumptions. Run the following checks simultaneously: 2A: Network Interfaces and Routing Look for: utun interfaces : Identify VPN/proxy TUN tunnels (ShadowRocket, Clash, Tailscale) Default route priority : Which interface handles default traffic Split routing : 0/1 + 128.0/1 → utun pattern means a VPN captures all traffic System proxy : HTTP/HTTPS proxy enabled on localhost ports 2B: RDP Client Process and Connections Key evidence to look for: Source IP 198.18.0.x : Traffic is being routed through ShadowRocket/proxy TUN tunnel No UDP connections from Windows process : Shortpath not established Only TCP 443 : Fallback to gateway WebSocket transport 2C: VPN/Proxy State 2D: Tailscale State (if running) The netcheck output reveals NAT type ( MappingVariesByDestIP ), UDP support, and public IP — valuable even when Tailscale is not the problem. 2E: Independent RDP Server Health Check (Direct PC) This step is critical for direct PC connections and useful for AVD/WVD/W365 as a falsification test: it proves the server side RDP stack is alive without relying on the Windows App client or any credentials. Use the bundled probe script: Example: A successful probe reports RDP server <host :<port is reachable and healthy (RDP + TLS). and means the problem is client side (auth, app state, proxy, or identity). A failed probe means the problem is server side or network (PC off, firewall, port unreachable, TLS interception). See references/direct pc and auth diagnostics.md for detailed interpretation of probe results. Step 3: Analyze Windows App Logs This is the most critical step. Windows App logs contain transport negotiation details that no network level test can reveal. Log location on macOS: Files are named: com.microsoft.rdc.macos v<version <date <time .log Important: Windows App log timestamps are UTC . The user's clock and Windows Event logs are usually local time. Convert all timestamps to a single timezone before building a timeline. Per session tracking: each connection attempt gets a unique activity GUID in braces. Aggregate events by GUID to understand the lifecycle of one attempt. See [references/windows app log analysis.md](references/windows app log analysis.md) for the GUID aggregation technique and [references/direct pc and auth diagnostics.md](references/direct pc and auth diagnostics.md) for the direct PC failure signatures. See [references/windows app log analysis.md](references/windows app log analysis.md) for detailed log parsing guidance. Quick Log Search Key Log Patterns Log Pattern Meaning Passed: InternetConnectivity Health check completed successfully TCP/IP Traffic Routed Through VPN: No/Yes Client detected VPN routing for TCP STUN/TURN Traffic Routed Through VPN: Yes Client detected VPN routing for STUN/TURN Passed URL: https://...wvd.microsoft.com/ Response Time: Nms Gateway reachability confirmed FetchClientOptions exception: Request timed out Critical : Client cannot get transport options from gateway Certificate validation failed TLS interception or DNS poisoning detected OnRDWebRTCRedirectorRpc rtcSession not handled WebRTC session setup not handled by client OneAuthError InteractionRequired A cached Microsoft account token cannot be refreshed silently No valid refresh tokens available in the cache No usable cached credentials for the auth request credential completion has been canceled The interactive sign in prompt was canceled GATEWAY(ERR): ... UserCancelled(8) Auth orchestration failed because sign in was canceled RDP WAN: Client connMonitor goto CMSTATE DROPPED Connection monitor detected a dropped session Channel::StartWrite failed / GetBuffer failed Transport is dead; client is writing to a closed socket ParseUserData: No data of type 0xc09 Non fatal — server answered MCS Connect; proves TCP path works IHAddMouseEventToPDU / IHAddMouseWheelEventToPDU Session is alive and receiving input Compare Working vs Broken Logs When possible, compare a log from when the connection worked (UDP) with the current log: A working log will contain the full health check block (InternetConnectivity, VPN routing detection, gateway URL tests). A broken log may show these entries missing entirely, or show certificate/timeout errors instead. Step 4: Determine Root Cause Based on collected evidence, identify the root cause category: Category A: VPN/Proxy Interference Evidence : Windows App source IP is 198.18.0.x , STUN/TURN routed through VPN, no UDP connections. Fix : Add DIRECT rules for AVD traffic in the proxy tool: Verify : Temporarily disable VPN/proxy, reconnect VDI, check if transport changes to UDP. Category B: ISP/Network UDP Restriction Evidence : Even with all VPNs off, still WebSocket. No UDP connections. FetchClientOptions timeout. Verify : Fix options : Try mobile hotspot (isolate home network from ISP) Check router NAT type (Full Cone NAT preferred) Enable UPnP on router Try IPv6 if available Contact ISP about UDP restrictions Category C: Client Health Check Failure Evidence : Log shows certificate validation errors at startup, health check block (InternetConnectivity, STUN/TURN detection) missing from log, FetchClientOptions timeout. This means the client cannot complete its diagnostic/capability discovery, preventing Shortpath negotiation. Possible causes : ISP HTTPS interception/MITM (especially in China) DNS poisoning returning incorrect IPs for Microsoft diagnostic endpoints Firewall blocking Microsoft telemetry endpoints Fix options : Change DNS to 8.8.8.8 or 1.1.1.1 (bypass ISP DNS) Route Microsoft traffic through a clean proxy Check if ISP injects certificates Category D: Server Side Shortpath Not Enabled Evidence : Log shows no STUN/TURN or Shortpath related entries at all (not even detection), but health checks pass and no errors. This means the AVD host pool does not have RDP Shortpath enabled. This requires admin action on the Azure portal. Category E: Client Identity / Expired Microsoft Account Poisoning (Direct PC and AVD) Evidence : The RDP protocol probe succeeds (server is healthy), but the Windows App log shows the OneAuth/MSAL chain: OneAuthError InteractionRequired No valid refresh tokens available in the cache AcquireTokenInteractively credential completion has been canceled User canceled sign in GATEWAY(ERR): CWVDTransport::OnOrchestrationHttpError error: UserCancelled(8) Fail OnDisconnected call The progress dialog may stay at "Configuring remote PC..." because the app is waiting for an interactive sign in prompt that is hidden or canceled. This can affect direct PC connections even when the expired account is unrelated to that PC, because the Windows App client shares the same auth orchestration across all connection types. Fix : Open Windows App → Settings → Accounts, sign out or remove the stale Microsoft work/school account, then fully quit (Cmd+Q) and relaunch the app. Retry the connection. See references/direct pc and auth diagnostics.md for the full signature set and troubleshooting steps. Category F: Server Side Reboot / Windows Update Evidence : A previously working session dropped suddenly, followed by reconnect failures. The Windows App log shows CMSTATE DROPPED and possibly Channel::StartWrite failed . The Windows PC's LastBootUpTime is close to the drop time, and Event ID 1074 shows MoNotificationUx.exe (Windows Update orchestrator) or another planned restart reason. Fix : Wait for the PC to finish booting, then reconnect. To prevent recurrence, set active hours / disable automatic restart during active hours in Windows Update settings, or schedule reboots when the user is not using the machine. If you have admin access, use Get CimInstance Win32 OperatingSystem for LastBootUpTime and Get WinEvent for Event ID 1074. See references/direct pc and auth diagnostics.md for the WSL/SSH encoded command technique. Step 5: Verify Fix After applying a fix, reconnect and verify the appropriate symptoms: For AVD/WVD/W365: 1. Check Connection Info — Transport Protocol should show UDP or UDP Multicast . 2. RTT should drop significantly (e.g., from 165ms to 40 60ms). 3. Verify with lsof: For Direct PC: 1. The progress dialog should disappear and the session window should appear. 2. The Windows App log for the new session should show mouse/keyboard input events ( IHAddMouseEventToPDU , IHAddKeyboardEventToPDU ) and no UserCancelled(8) errors. 3. If the issue was an expired Microsoft account, confirm that only valid accounts remain in Windows App → Settings → Accounts. For server reboots: 1. Verify the PC is reachable again with ping and scripts/

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