ESP32 Disconnects Randomly from Wi-Fi

ESP32 Disconnects Randomly from Wi-Fi #

An ESP32 that boots and connects successfully to Wi-Fi - only to disconnect minutes or hours later - is one of the most frustrating issues to debug. These random or periodic disconnections often don't follow a clear pattern and may happen under load, at idle, or after specific intervals.

This guide walks through the most common reasons for unexpected disconnections and how to fix them for stable long-term operation.

Common Symptoms #

You may observe:

• Serial monitor outputs like:

[WiFi-event] Disconnected. Reason: 200

• Disconnection after a set interval (e.g., 1 hour)
• ESP32 reboots when Wi-Fi disconnects (if not handled properly in code)
• Works fine on some routers, fails on others

These clues point to one of several common causes.

Key Causes of Random Wi-Fi Disconnection #

📶 Weak or Unstable Wi-Fi Signal #

If the ESP32 is too far from the router or surrounded by interference (walls, appliances, metal), the signal may fluctuate. This causes dropped packets and ultimately disconnects.

You can check RSSI with:

Serial.println(WiFi.RSSI());

Values weaker than -75 dBm often indicate unstable performance.

⏱ Wi-Fi Sleep Mode Interferes with Stability #

By default, the ESP32 uses a power-saving Wi-Fi mode that periodically disables parts of the transceiver. On some routers, this causes synchronization problems, especially under poor signal.

To disable it:

WiFi.setSleep(false);

Place this before WiFi.begin() in your setup code.

🔧 Router DHCP Timeout or Lease Issues #

Many routers issue short DHCP leases (e.g., 1 hour). If the ESP32 doesn’t renew in time or the lease is lost during a signal glitch, the router may drop the connection.

This often results in disconnection after predictable time intervals (like every 3600 seconds).

To resolve:

• Set a longer lease time in router settings (e.g., 24h or infinite)

• Or assign a static IP with:

WiFi.config(local_IP, gateway, subnet, dns);

📡 RF Interference or Channel Crowding #

The 2.4GHz band used by ESP32 is shared with Bluetooth, microwaves, and many other Wi-Fi networks. If your network overlaps with many others on the same or nearby channels (e.g., channel 6), congestion can cause disconnects.

Use a Wi-Fi analyzer app to scan channels and select a less crowded one in your router’s settings.

Best Practices to Prevent Random Disconnects #

✅ Disable Wi-Fi Power Save Mode #

This is the single most effective fix for long-running applications:

WiFi.setSleep(false);

This ensures the ESP32 maintains a full-time connection and avoids router sync issues.

✅ Add Reconnection Logic #

Detect disconnects and automatically reconnect using event handlers:

WiFi.onEvent([](WiFiEvent_t event){
  if (event == SYSTEM_EVENT_STA_DISCONNECTED) {
    Serial.println("WiFi lost, reconnecting...");
    WiFi.reconnect();
  }
});

Or use a timer to check WiFi.status() and reconnect periodically.

✅ Use Static IP on Unreliable Routers

By setting a fixed IP, you bypass DHCP lease expiration issues.

✅ Improve Antenna Position or Shielding

Even with onboard PCB antennas, signal quality improves dramatically if:

• The ESP32 is mounted vertically

• Kept away from metal enclosures

• Uses an external antenna (if available on your module)

Conclusion #

Random Wi-Fi disconnects on ESP32 often stem from weak signal, router quirks, or power-saving behaviors. These aren’t bugs in your code - but environmental or configuration issues.

To keep the ESP32 connected:

• Disable sleep mode

• Improve signal quality

• Handle disconnects in software

• Consider a static IP or longer DHCP lease

A stable Wi-Fi connection is key to reliable IoT systems - and with the right tweaks, ESP32 can maintain a connection for days or even weeks without issue.