Diagnosing and Fixing Android Wi‑Fi Issues with ADB

Why we use -b all: Android stores logs in multiple buffers (main, system, radio). Wi‑Fi events are logged in the radio buffer, but some higher‑level events appear in system. Using -b all guarantees we don’t miss anything.

Step 4 – Understanding Common Log Patterns

Below is a short, annotated excerpt of what a typical Wi‑Fi failure looks like. Real logs are longer, but the same markers repeat.

04-12 14:23:01.123  1123  1123 I wifi    : WiFiStateMachine CMD_CONNECT_NETWORK: networkId=5
04-12 14:23:01.145  1123  1123 D wifi    : DhcpStateMachine CMD_START_DHCP: iface=wlan0
04-12 14:23:03.567  1123  1123 W wifi    : DhcpStateMachine: DHCP failed, error=2
04-12 14:23:03.569  1123  1123 E wifi    : NetworkAgent: Network validation failed (no internet)
04-12 14:23:04.001  1123  1123 I wifi    : SupplicantStateMachine CMD_DISCONNECT
04-12 14:23:04.010  1123  1123 I wifi    : SupplicantStateMachine EVENT_DISCONNECTED

Key tags to look for:

• I wifi – Informational messages from the Wi‑Fi manager.
• D wifi – Debug messages, often DHCP details.
• W wifi – Warnings; a common sign of a problem.
• E wifi – Errors that usually require action.

Notice the DHCP failed and Network validation failed lines. Those are the two most frequent culprits:

• DHCP failed, error=2 – The device could not obtain an IP address from the router.
• Network validation failed (no internet) – The router gave an IP, but the device could not reach Google’s connectivity check.

By identifying which line appears first, you can decide whether the problem is at the router‑DHCP level or at higher‑level DNS/Internet access.

Step 5 – Quick Fixes Based on Log Findings

Below we map the most common log signatures to concrete actions. Perform the actions in the order presented; many issues resolve after the first step.

5.1 – DHCP Failure (error=2 or error=3)

• Action 1 – Forget and Re‑add the Network
  1. On the phone, go to Settings → Network & internet → Wi‑Fi.
  2. Tap the gear icon next to the problem SSID and choose Forget.
  3. Reconnect by selecting the SSID again and entering the password.

  Forgetting forces the device to request a fresh lease, clearing any stale DHCP cache.

• Action 2 – Restart the Router

  Power‑cycle the router for 30 seconds. A reboot clears its DHCP table and often resolves address conflicts.

• Action 3 – Assign a Static IP via ADB

  If the router’s DHCP server is unreliable, you can give the device a static IP using the hidden ip command. This method is advanced and should be used only when you control the network.

  # Replace 192.168.1.100/24 with an unused address in your subnet
  adb shell su -c "ifconfig wlan0 192.168.1.100 netmask 255.255.255.0 up"
  # Set the default gateway
  adb shell su -c "route add default gw 192.168.1.1 dev wlan0"

  Warning: Not all devices allow su without root. If the command fails, revert to DHCP.

5.2 – Network Validation Failed (No Internet)

• Action 1 – Check DNS Settings
  1. Open Settings → Network & internet → Advanced → Private DNS.
  2. Set it to Off or configure a known provider (e.g., dns.google).

  Incorrect Private DNS can block the validation ping to connectivitycheck.gstatic.com.

• Action 2 – Disable Wi‑Fi Optimizations

  Battery‑saving modes sometimes throttle Wi‑Fi. Disable them temporarily:

  1. Settings → Battery → Battery saver → Turn off (or set to “Never” for Wi‑Fi).
  2. Settings → Wi‑Fi → Advanced → Wi‑Fi optimization → Off (if present).
• Action 3 – Reset Network Settings

  This clears all saved Wi‑Fi, Bluetooth, and VPN configurations, forcing a clean slate.

  adb shell am start -a android.settings.RESET_NETWORK_SETTINGS

  Confirm the dialog on the phone. After the reset, reconnect to the Wi‑Fi network.

5.3 – Repeated Supplicant State Changes (DISCONNECTED ↔ SCANNING)

• Action – Update Wi‑Fi Driver via OTA

  Some devices ship with a buggy Wi‑Fi driver that is fixed in a later OTA (over‑the‑air) update. Check Settings → System → System update. If an update is available, install it and retest.

• Action – Disable “Wi‑Fi Scanning” in Location Settings

  On Android 10+ the system may scan for Wi‑Fi networks even when Wi‑Fi is off, causing extra state churn.

  1. Settings → Location → Wi‑Fi scanning → Off.
  2. Settings → Location → Bluetooth scanning → Off (optional).

Step 6 – Advanced Log‑Based Diagnosis

If the quick fixes didn’t solve the problem, dive deeper into the log. Below is a table of frequent error strings and what they usually indicate.

Search the log for any of the strings above using grep. For example:

grep -i "handshake failed" wifi_log.txt

If you find a match, apply the corresponding action.

Step 7 – Verifying the Fix

After applying a fix, repeat the log capture (Step 3) to confirm the offending lines disappear.

Step 8 – Optional: Automating Log Capture for Future Issues

For power users who encounter intermittent Wi‑Fi glitches, you can create a tiny shell script that starts logging, waits a configurable period, and then saves the file with a timestamp.

# save as capture_wifi.sh and make executable (chmod +x)
#!/bin/bash
TS=$(date +%Y%m%d_%H%M%S)
FILE="wifi_${TS}.txt"
adb logcat -b all -v threadtime | grep -i "wifi" > "$FILE" &
PID=$!
# Capture for 60 seconds
echo "Capturing Wi‑Fi log for 60 seconds…"
sleep 60
kill $PID
echo "Log saved to $FILE"

Run it whenever you notice a glitch; the timestamped file helps you build a personal archive of Wi‑Fi behavior across different networks.

Troubleshooting Common Log‑Capture Problems

• Log file is empty

  Make sure the device is not in Doze mode. Temporarily disable Doze by running adb shell dumpsys deviceidle disable. Also verify that the USB cable is not a charge‑only cable.

• Permission denied when running su commands

  Most consumer devices do not grant root privileges to ADB. Stick to the non‑root methods (forget network, reset settings). If you own a rooted device, ensure the su binary is present and that you grant permission when prompted.

• “device offline” after reconnecting

  Disconnect and reconnect the USB cable, then run adb kill-server && adb start-server. On some devices you must re‑enable USB debugging after a reboot.

When to Escalate to Manufacturer Support

If after exhausting the steps above the device still cannot maintain a Wi‑Fi connection on multiple routers, the problem is likely hardware‑related (e.g., a failing Wi‑Fi antenna) or a deep firmware bug. In that case:

1. Gather the latest log file.
2. Note the device model, Android version, and any custom ROM or carrier firmware.
3. Contact the manufacturer’s support portal and attach the log. Mention the specific error strings you observed.

Providing a concise log excerpt often speeds up the troubleshooting process, because the support engineers can reproduce the exact failure path.

Summary

Android Wi‑Fi problems can be frustrating, but the system logs give us a transparent view of what’s going wrong. By enabling ADB, capturing a focused Wi‑Fi log, interpreting the most common error patterns, and applying the targeted fixes described above, you can resolve the majority of connectivity issues without rooting or flashing custom firmware. Keep the troubleshooting flow handy, and you’ll turn a vague “Can’t connect” message into a concrete, solvable problem.