net: swap WiFi roles — fast T3U (wlan1) hosts AP, onboard (wlan0) carries uplink

- yaris_uplink.py: PRIMARY_INTERFACE=wlan0, AP_INTERFACE=wlan1, AP_CONNECTION=Hotspot-local
- install_netwatch.sh: WLAN=wlan0, WLAN_FB=wlan1, AP on wlan1
- _ap_client_count() reads the AP interface instead of hardcoded wlan0

deploy/install_netwatch.sh

@@ -7,13 +7,15 @@
 # already exist (see PLAN.md Phase 6). The optional "phone-hotspot" profile is
 # created through the Settings page.
 #
-# Since Phase 23+: all WiFi traffic (hotspot AP, phone client, home client)
-# runs on wlan1 (TP-Link T3U dongle). wlan0 (onboard) is disabled.
+# Since 2026-08-12: the fast TP-Link T3U (wlan1) hosts the in-car AP
+# ("Hotspot-local"), while the onboard BCM43438 (wlan0) carries the internet
+# uplink (home-wifi / phone-hotspot).
 set -euo pipefail
 
 REPO_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")/.." && pwd)"
-WLAN=wlan1   # T3U dongle — change to wlan0 if reverting to onboard
-WLAN_FB=wlan0  # onboard fallback
+WLAN=wlan0   # onboard — internet uplink
+WLAN_FB=wlan1  # T3U — uplink fallback
+AP_IFACE=wlan1 # T3U — hosts the in-car AP
 
 sudo systemctl stop yaris-uplink-wait.service 2>/dev/null || true
 sudo systemctl stop yaris-netwatch.timer yaris-netwatch.service 2>/dev/null || true
@@ -26,10 +28,11 @@ sudo install -m 644 "$REPO_DIR/deploy/yaris-hotspot-dns.conf" \
 sudo install -m 755 "$REPO_DIR/deploy/90-yaris-uplink" \
     /etc/NetworkManager/dispatcher.d/90-yaris-uplink
 
-# Bind all connections to the T3U dongle (wlan1)
+# Bind the internet uplink to the onboard radio (wlan0)
 sudo nmcli connection modify home-wifi connection.interface-name "$WLAN"
-sudo nmcli connection modify Hotspot \
-    connection.interface-name "$WLAN" \
+# The in-car AP lives on the fast T3U (wlan1)
+sudo nmcli connection modify Hotspot-local \
+    connection.interface-name "$AP_IFACE" \
     ipv4.method shared \
     ipv4.addresses 10.42.0.1/24
 if nmcli connection show phone-hotspot >/dev/null 2>&1; then
@@ -40,8 +43,8 @@ if nmcli connection show phone-hotspot >/dev/null 2>&1; then
         802-11-wireless.mtu 1400
 fi
 
-# Create wlan0 fallback profiles (lower autoconnect-priority so wlan1 wins)
-# home-wifi-fb: same SSID as home-wifi but on wlan0
+# Create wlan1 fallback profile (lower autoconnect-priority so wlan0 wins)
+# home-wifi-fb: same SSID as home-wifi but on wlan1 (T3U)
 HOME_SSID=$(nmcli -g 802-11-wireless.ssid connection show home-wifi 2>/dev/null || true)
 HOME_PSK=$(sudo nmcli -g 802-11-wireless-security.psk connection show --show-secrets home-wifi 2>/dev/null || true)
 if [ -n "$HOME_SSID" ] && [ -n "$HOME_PSK" ]; then

deploy/yaris_uplink.py

@@ -11,9 +11,13 @@ import uuid
 
 PHONE_CONNECTION = "phone-hotspot"
 HOME_CONNECTION = "home-wifi"
-AP_CONNECTION = "Hotspot"
-PRIMARY_INTERFACE = "wlan1"    # TP-Link T3U dongle — preferred
-FALLBACK_INTERFACE = "wlan0"   # onboard — used if T3U is absent
+AP_CONNECTION = "Hotspot-local"
+# 2026-08-12 swap: the fast TP-Link T3U (wlan1) hosts the in-car AP so phones
+# get 5GHz AC throughput; the weak onboard BCM43438 (wlan0) carries the
+# internet uplink (home-wifi / phone-hotspot), which is background traffic.
+AP_INTERFACE = "wlan1"
+PRIMARY_INTERFACE = "wlan0"    # onboard — internet uplink
+FALLBACK_INTERFACE = "wlan1"   # T3U — uplink fallback if onboard is absent
 STATUS_PATH = "/var/lib/yaris-obd/uplink-status.json"
 PHONE_KEYFILE = (
     "/etc/NetworkManager/system-connections/"
@@ -199,7 +203,7 @@ def write_status(action, error=None):
 
 
 def restore_fallback():
-    """Try home-wifi on wlan1. wlan0 AP is permanent and never touched."""
+    """Try home-wifi on the uplink interface. The AP on wlan1 is never touched."""
     if activate(HOME_CONNECTION):
         write_status("connected_home")
         return True
@@ -208,10 +212,10 @@ def restore_fallback():
 
 
 def _ap_client_count():
-    """Return number of stations connected to the AP on wlan0."""
+    """Return number of stations connected to the AP on wlan1 (T3U)."""
     try:
         proc = subprocess.run(
-            ["iw", "dev", "wlan0", "station", "dump"],
+            ["iw", "dev", AP_INTERFACE, "station", "dump"],
             capture_output=True, text=True, timeout=5,
         )
         return proc.stdout.count("Station ")
@@ -220,7 +224,7 @@ def _ap_client_count():
 
 
 def check_uplink():
-    """Manage internet uplink on wlan1 only. wlan0 is a permanent AP, never touched."""
+    """Manage internet uplink on wlan0 only. wlan1 AP is never touched."""
     current = active_connection()
     phone_configured = connection_exists(PHONE_CONNECTION)
 
@@ -240,7 +244,7 @@ def check_uplink():
         return _connect_home_or_idle()
 
     if phone_configured:
-        # Only take down the phone hotspot if it's up — never touch the AP on wlan0
+        # Only take down the phone hotspot if it's up — never touch the AP on wlan1
         was_phone = current == PHONE_CONNECTION
         if was_phone:
             run_nmcli("connection", "down", PHONE_CONNECTION, check=False)
@@ -281,7 +285,7 @@ def check_uplink():
 
 
 def _connect_home_or_idle():
-    """Try home-wifi on wlan1. wlan0 AP is never touched."""
+    """Try home-wifi on the uplink interface. The AP on wlan1 is never touched."""
     if activate(HOME_CONNECTION):
         write_status("connected_home")
         return True