Stabilize Wi-Fi by preventing AP fallback flapping

src/main.py

@@ -22,6 +22,8 @@ class Supervisor(threading.Thread):
         self.rtc = rtc
         self._stop_event = threading.Event()
         self._ntp_synced = False
+        self._wifi_down_streak = 0
+        self._ap_enable_after_cycles = 4  # 4 * 15s = 60s sustained Wi-Fi down
 
     def stop(self) -> None:
         self._stop_event.set()
@@ -32,17 +34,26 @@ class Supervisor(threading.Thread):
                 self.nm.refresh_state()
                 snapshot = self.state.snapshot()
 
-                should_have_ap = not (snapshot["wifi_connected"] and snapshot["internet_available"])
                 in_grace = time.time() < self.state.ap_grace_until
+                wifi_connected = bool(snapshot["wifi_connected"])
 
-                if should_have_ap and not snapshot["ap_mode"] and not snapshot["connecting"] and not in_grace:
-                    LOG.warning("No active internet, enabling AP fallback")
+                if wifi_connected:
+                    self._wifi_down_streak = 0
+                else:
+                    self._wifi_down_streak += 1
+
+                if (
+                    self._wifi_down_streak >= self._ap_enable_after_cycles
+                    and not snapshot["ap_mode"]
+                    and not snapshot["connecting"]
+                    and not in_grace
+                ):
+                    LOG.warning(
+                        "Wi-Fi disconnected for %ss, enabling AP fallback",
+                        self._wifi_down_streak * 15,
+                    )
                     self.nm.start_ap()
 
-                if not should_have_ap and snapshot["ap_mode"]:
-                    LOG.info("Internet restored, disabling AP")
-                    self.nm.stop_ap()
-
                 if snapshot["internet_available"] and not self._ntp_synced:
                     ok, msg = self.rtc.sync_ntp_and_rtc()
                     if ok:

src/network_manager.py

@@ -91,16 +91,14 @@ class NetworkManager:
             return False
         if not self.has_default_route():
             return False
-        try:
-            with socket.create_connection(("1.1.1.1", 53), timeout=2):
-                pass
-        except OSError:
-            return False
-        try:
-            socket.gethostbyname("pool.ntp.org")
-        except OSError:
-            return False
-        return True
+        # Avoid DNS lookups here; transient resolver issues should not trigger AP mode flapping.
+        for target in (("1.1.1.1", 53), ("8.8.8.8", 53)):
+            try:
+                with socket.create_connection(target, timeout=2):
+                    return True
+            except OSError:
+                continue
+        return False
 
     def _service_action(self, action: str, unit: str) -> bool:
         return self._run_quiet(["systemctl", action, unit], timeout=20)