141 lines
10 KiB
Markdown
141 lines
10 KiB
Markdown
---
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title: "iPhone Mirroring Hangs on 'Connecting…' — AWDL Data Stall (27.0 Beta)"
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domain: troubleshooting
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category: macos
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tags: [macos, iphone-mirroring, continuity, awdl, rapport, quic, tailscale, mullvad, beta, channel-validation, aimesh, quicktime, usb]
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status: published
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created: 2026-06-09
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updated: 2026-06-14
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---
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# iPhone Mirroring Hangs on 'Connecting…' — AWDL Data Stall (27.0 Beta)
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## Update 2026‑06‑14 — root cause refined (and what is *not* the cause)
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> Re‑investigated end‑to‑end on the **same OS seed** (build `26A5353q`, unchanged). The original "AWDL data stall / nothing local was wrong" call was close but mis‑attributed the secondary causes. Corrected understanding below — **practical outcome is unchanged: no user‑side fix, wait for a new seed.**
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**Refined root cause — the AWDL _bulk‑data_ path can't hold a 5 GHz channel.**
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Pulled the iPhone's own logs over USB (`sudo log collect --device --last 8m --output ~/Desktop/x.logarchive`). The kernel Wi‑Fi driver (`AppleBCMWLAN`, `wlan0:com.apple.p2p.awdl0`) shows, over 8 min on infra channel 36:
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- `isValidChannel … not match … channel 36 band 0x10` — **238×** (vs 32 passes): AWDL rejects the channel for the P2P group.
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- `Disable Steering on Timeout` — **159×**: can't steer to a better channel.
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- `isInfraRealtimePacketThresholdAllowed allowed:0` — **169/451**: bulk realtime packets blocked ~37 % of the time.
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Net: the Mac's `awdl0` carries **~90 B/s** (control keepalive only; real video is hundreds of KB/s–MB/s). The feed is **starved, not corrupted** — "missing icons" = frame data that never arrived (zero decode/`kVT` errors logged).
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**What is NOT the cause (each tested and ruled out):**
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- **Tailscale is not a hard RF blocker.** With accept‑routes on but **no exit node**, mirroring connects. Tailscale only *intermittently* breaks the **control plane** (QUIC endpoint binding → "Connection Interrupted"); with Tailscale **off** the session establishes but the **bulk video still starves**. So the old "disable Tailscale" step lets you *connect* but does **not** fix the video. (Mechanism is control‑plane endpoint flapping, not the RF‑layer block the original note implied.)
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- **Not congestion.** Router `chanim_stats` on ch36 = **90 % idle, 86 % txop, 3 % obss**; Mac link −39 dBm / −94 dBm noise. Pristine.
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- **Not the channel number — the whole UNII‑1 block is AWDL‑hostile on this seed.** ch36 → starved feed (~90 B/s, glitchy). **ch44** (same 36–48 block) → **worse**: times out before media starts (`Failed to find endpoint`, `MediaContinuityKit.TaskTimeoutError`, 0 B/s). Both fail → the validator rejects the entire UNII‑1 block, not just primary 36.
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- **ch149 (UNII‑3) untested.** It's the iPhone's preferred AWDL anchor and a *different* block, so it's the one channel that might work — but it's busier and the AiMesh controller resists pinning it (see infra notes). Deferred as not worth the disruption for a beta bug.
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**Wired workaround (works today, no AWDL):**
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iPhone Mirroring is **wireless‑only — there is no USB transport** (confirmed: cable connected throughout, every attempt still used `awdl0`). For a wired view of the screen:
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> **QuickTime Player → File → New Movie Recording → ⌄ next to record → select the iPhone** = full‑rate USB‑C screen mirror (view + record). Does **not** give remote control (tap/type) — that's unique to iPhone Mirroring.
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**Infra notes (RT‑AX82U, AiMesh controller):**
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- Router SSH is on **port 1025** (not 22); creds in Ansible vault (`router_username` / `router_password`).
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- The 5 GHz channel is **AiMesh‑coordinated** and **resists CLI changes** — `wl chanspec` / nvram `wl1_chanspec` get re‑asserted by `acsd2` + AiMesh within seconds, even after `restart_wireless`. Only setting Control Channel to an **explicit value in the Web UI** holds mesh‑wide. Left "Auto" → acsd2 picks **36** (the cleanest channel).
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- Any channel change triggers a **mesh re‑sync (~1 min) that drops all Wi‑Fi**; during it MajorAir falls back to the iPhone's **USB Personal Hotspot** (`en7` / `172.20.10.x`) and won't auto‑rejoin home Wi‑Fi while the hotspot feeds it internet (manual Wi‑Fi‑menu join needed).
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- **Current state: 5 GHz on ch44/80** (same clean UNII‑1 spectrum as 36; left here to avoid another re‑sync — the Deck streams identically on 44).
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**Revisit checklist — when a new iOS/macOS seed ships:**
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1. Confirm the seed changed: `sw_vers` BuildVersion ≠ `26A5353q` (both Mac and iPhone).
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2. Tailscale **off**; iPhone on home Wi‑Fi, near the Mac, **Personal Hotspot off**.
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3. Open iPhone Mirroring.
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4. Measure `awdl0` RX over a few seconds — **target hundreds of KB/s** (real video), not ~90 B/s.
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5. Pull the iPhone log (`log collect --device`) and check `isValidChannel` now **passes** for the infra channel.
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6. If still starved → no user fix; re‑file Feedback Assistant and keep waiting.
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---
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## Symptom
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iPhone Mirroring on the Mac sits on **"Connecting…"** forever and never shows the iPhone screen.
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- Mac: **macOS 27.0 dev beta** (build 26A5353q), MajorAir
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- iPhone: **Major16Pro / iPhone17,1, iOS 27.0 dev beta**, same Apple ID (maj.linux@gmail.com)
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## Root cause (conclusion)
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A **bug in the iPhone Mirroring beta** (both devices on the `.0` developer seeds). The connection
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authenticates, the AWDL peer-to-peer link comes up, the TLS handshake starts — then **bidirectional
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data stalls ~2 seconds in** and the link is torn down. Deterministic, reproduces every attempt.
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**Nothing in the local configuration was wrong.** Filed via Feedback Assistant; expected to clear in
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a future seed.
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Two *real but secondary* network-layer issues were found and fixed along the way (see below) — they
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can block mirroring independently, but were not the cause of the final 2-second stall.
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## The smoking gun (unified log)
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Per connection attempt the sequence is always:
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```
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rapportd: Session start … linkType "AWDL", error "NoError" # link negotiated OK
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iPhone Mirroring: Installing verify block for 1 authorized peer key(s)
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boringssl: TLS client read_server_hello # iPhone DID respond
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quic: path over awdl0 received event established / promoted to primary
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nw_flow_connected: Transport protocol connected (socket)
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… flow:connect_stalled @2.003s # stalls exactly ~2s in
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quic_conn_log_summary: Connection attempts: 6, RETRY received: no, PTOs: 5 # packets sent, zero ACKs
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[C1.1.1 … awdl0 … failed socket-flow (unsatisfied (No network route))] # link dropped (symptom, not cause)
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```
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The connection is pinned to AWDL (`allowed subtypes: wifi_awdl, prohibit fallback`), so once the
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AWDL data path stalls there is no fallback and it fails. "No network route" is the *result* of the
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teardown, not the trigger. The trigger is that after the initial handshake packets, **sustained
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QUIC traffic over AWDL gets no ACKs** (PTOs).
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## Investigation path (what was ruled out)
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- **Discovery / proximity** — healthy throughout. BLE + Bonjour resolve the iPhone; `rapportd`
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sees it with good RSSI, same iCloud (`DF < MyiCloud >`), `WiFiP2P`.
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- **Tailscale (full-tunnel)** — with Tailscale connected, the attempt died at "No network route"
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*before* even reaching AWDL. Cause: `RouteAll: true` (accept-routes / a `::/0` advertised route)
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installs **IPv6 default routes via `utun`** (`default → fe80::%utun0..3`) that black-hole the
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IPv6 path AWDL needs. **`tailscale down` is NOT enough** — it only sets `WantRunning=false`; the
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macOS VPN *configuration* (`scutil --nc list` showed it still `Connected`) and the system
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extension keep reasserting the routes across reboots. Must disable in **System Settings → VPN**.
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- **Mullvad** — `mullvad-daemon` running; **"Local network sharing" was set to `block`**, which
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blocks LAN/AWDL/multicast. Changed to **`allow`** (`mullvad lan set allow`). Kill-switch was off.
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- **macOS firewall** — off. No Little Snitch/LuLu app installed.
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- **Lockdown Mode** — off (iPhone).
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- **OS-version mismatch** — ruled out; both Mac and iPhone on 27.0 dev beta.
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- **Device trust / re-pairing** — there is **no local pairing record on the Mac** to reset.
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`rapportd` lists the iPhone as **"PairedSys Conjectured"** = trust is *derived from the shared
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Apple ID*, not a manual pairing. Forgetting the Mac on the iPhone does not force re-setup; the
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Mac just re-derives the association from iCloud and reconnects. (App containers
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`~/Library/Containers/com.apple.ScreenContinuity` and the rapport stores held no device record;
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the "1 authorized peer key" lives in the protected system keychain.)
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- **Reboots / airplane-mode toggle / Mac-side AWDL + rapportd reset** — no change.
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## Secondary issues found & fixed (do these regardless)
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1. **Mullvad** — set **Local network sharing = allow** (done). Required for any LAN/AWDL feature.
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2. **Tailscale** — do not run **full-tunnel / accept a `::/0` route** while mirroring; it installs
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IPv6 default routes via `utun` that kill the local link. Toggle the VPN off in System Settings
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(not just `tailscale down`) if it ever needs to be fully out of the path.
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3. **Orphaned Little Snitch network extension** — the app was uninstalled but its
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`at.obdev.littlesnitch.networkextension` is still `[activated enabled]`
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(`systemextensionsctl list`). Remove via **System Settings → General → Login Items &
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Extensions → Network Extensions**. A zombie filter extension with no app behind it can
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black-hole traffic.
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## Status / next steps
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- **No user-side fix.** Filed in Feedback Assistant.
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- Debug capture saved: `~/Desktop/iPhoneMirroring-debug-20260609-0026.txt` (summary + log narrative).
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For a full report, trigger a sysdiagnose (**⌃⌥⇧⌘ + .**) right after reproducing and attach it.
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- VPNs restored after session: Tailscale back up; Mullvad left disconnected with LAN sharing = allow.
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## Useful diagnostic commands (for next time)
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```bash
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# Connection narrative
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log show --last 10m --style compact --predicate \
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'(subsystem == "com.apple.MediaContinuityKit") OR (process == "iPhone Mirroring")' | tail -60
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# rapport / AWDL negotiation
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log show --last 5m --style compact --predicate 'process == "rapportd"' | grep -iE "AWDL|Pair|Session"
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# VPN config really on? (CLI "down" lies)
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scutil --nc list ; scutil --nc status "Tailscale"
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# IPv6 default routes hijacked by utun?
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netstat -rn -f inet6 | awk '$1=="default"{print}'
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# Active system extensions (filters/VPNs)
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systemextensionsctl list
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# Mullvad LAN sharing
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mullvad lan get
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```
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## Related
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- `macos-mirrored-notification-alert-loop.md` (other Continuity issue)
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- Hosts/VPN context: MajorTwin project doc (Tailscale tailnet, 100.x addresses)
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