Wifi Diagnostics

Wi-Fi Diagnostics

Diagnose Wi-Fi connectivity issues with signal analysis, channel scanning, and speed tests.

Requirements

• Linux with nmcli, iwconfig, or iw
• curl for speed tests
• Optional: dig for DNS diagnostics
• Some commands require sudo for wireless scanning

Instructions

Connection info

# Current network details
nmcli -t -f active,ssid,signal,chan,freq,bssid dev wifi | grep '^yes'

# Interface details
iwconfig 2>/dev/null | grep -E 'ESSID|Quality|Bit Rate'

# IP and gateway
ip route | grep default
ip addr show | grep 'inet '

Channel scan

# Nearby networks (may need sudo)
nmcli dev wifi list

# Channel utilization summary
nmcli -t -f chan,signal dev wifi list | sort -t: -k1 -n | \
  awk -F: '{ch[$1]++; sig[$1]+=$2} END{for(c in ch) printf "Ch %s: %d networks, avg signal %d%%\n", c, ch[c], sig[c]/ch[c]}'

Speed test (no dependencies)

# Download test (~10MB)
curl -o /dev/null -s -w "Download: %{speed_download} bytes/sec (%{time_total}s)\n" https://speed.cloudflare.com/__down?bytes=10000000

# Upload test (~10MB)
dd if=/dev/zero bs=1M count=10 2>/dev/null | curl -X POST -d @- -s -w "Upload: %{speed_upload} bytes/sec\n" https://speed.cloudflare.com/__up

DNS diagnostics

dig google.com | grep "Query time"
ping -c 5 8.8.8.8 | tail -1
ping -c 5 1.1.1.1 | tail -1

Output format

## 📶 Wi-Fi Diagnostics — <timestamp>

**Network**: MyWiFi | **Channel**: 6 (2.4GHz) | **Signal**: 72%

| Test | Result | Status |
|------|--------|--------|
| Signal | -45 dBm (72%) | 🟢 Good |
| Download | 48.2 Mbps | 🟢 Good |
| Upload | 12.1 Mbps | 🟡 Fair |
| DNS Latency | 15ms | 🟢 Good |
| Ping (8.8.8.8) | 22ms avg | 🟢 Good |

**Channel Congestion**: Ch 6 has 8 networks. Consider switching to Ch 1 or 11.

**Thresholds**: Signal: 🟢>60% 🟡30-60% 🔴<30% | Speed: 🟢>25Mbps 🟡>5Mbps 🔴<5Mbps

Edge Cases

• No Wi-Fi adapter: Detect with iw dev. Report if no wireless interface found.
• Ethernet only: Note that diagnostics apply to Wi-Fi only — ethernet has different tools.
• 5GHz vs 2.4GHz: Report which band is in use. Channel recommendations differ per band.
• VPN active: Speed tests may be affected by VPN. Note if a VPN interface is detected.
• nmcli unavailable: Fall back to iwconfig and iw.

Security

• Speed tests send data to external servers (Cloudflare) — fine for diagnostics.
• Wi-Fi scan reveals nearby network names — don't share in public contexts.
• Never expose Wi-Fi passwords in diagnostic output.