4 October 2025
Tech Tips

Troubleshoot network speed and reliability

  1. Define the problem
  • What’s happening? Slow speeds, frequent disconnects, high latency, jitter, or packet loss?
  • When does it occur? Time of day, after heavy usage, on all devices or just one?
  • Is it wired or wireless (or both)?
  • Note any recent changes (new hardware, software updates, new devices, ISP outage).
  1. Establish a baseline
  • Run a quick test on a wired connection (best baseline): connect a device directly to the modem/router with an Ethernet cable and run a speed test (supported by your preferred service, e.g., speedtest.net).
  • Record download/upload speeds, ping, and any variability.
  • Repeat on multiple devices and at different times of day to see patterns.
  • Test on wireless devices to compare with wired performance.
  1. Check the physical layer
  • Cables: inspect Ethernet/Cat5e/Cat6 cables for damage. Swap in a known-good cable (prefer Cat5e/Cat6).
  • Ports: try different ports on the router/switch, and test the device on a different port.
  • Modem/router: reboot both modem and router. If you have a combined gateway, restart it as well.
  • Power: ensure devices have stable power; avoid power strips with other heavy loads if possible.
  1. Inspect the local network hardware
  • Firmware: check for and install firmware updates on your modem, router, and any range extenders.
  • Placement: place the router centrally, elevated, away from thick walls, microwaves, and cordless phones to improve coverage.
  • Interference: for Wi‑Fi, check channel usage. Use 2.4 GHz if you need range, or 5 GHz for speed (less interference). Consider changing the channel to a less congested one.
  • Band steering and QoS: temporarily disable QoS or band steering to see if performance improves.
  1. Test wired vs wireless
  • If wired is consistently fast but wireless is slow, focus on Wi‑Fi optimization.
  • If both are slow, the issue may be modem/ISP, or a wide network problem.
  1. Run basic network diagnostics On Windows
  • Command prompt:
    • ipconfig /all (check IP, gateway, DNS)
    • ping -n 20 8.8.8.8 (latency to Google DNS)
    • ping -n 20 your_default_gateway (latency to router)
    • tracert 8.8.8.8 (path to destination)
    • pathping 8.8.8.8 (packet loss along path)
  • Netstat -ano (check for abnormal connections) On macOS/Linux
  • ifconfig or ip a
  • ping -c 20 8.8.8.8
  • traceroute 8.8.8.8 (or tracepath)
  • mtr -rwzbc100 8.8.8.8 (if available)
  • dig +short example.com (DNS resolution) Tips:
  • Look for high ping, high jitter, or repeated packet loss.
  • If packet loss appears on wireless but not wired, the issue is likely radio interference or coverage.
  1. Check DNS and browser-related issues
  • Try a different DNS (e.g., set DNS to 1.1.1.1 and 8.8.8.8) to see if lookup delays affect perceived speed.
  • Clear DNS cache: ipconfig /flushdns (Windows) or sudo dscacheutil -flushcache; sudo killall -HUP mDNSResponder (macOS).
  • Test with a different device and/or a wired connection to rule out device-specific problems.
  1. Identify interference and environment (wireless)
  • Use a Wi‑Fi analyzer (apps or software) to see channel congestion and signal strengths.
  • If many neighbors use the same channel, switch to a less crowded channel or use a 5 GHz network (if your devices support it).
  • Consider adding a mesh system or Wi‑Fi extender only where needed; avoid overloading a single router with too many extenders.
  1. Check for congestion and background activity
  • On devices: close bandwidth-heavy apps (video streaming, cloud backups, large downloads, updates).
  • Check for malware or crypto mining/unknown processes that could be consuming bandwidth. Run a security scan.
  • If you have smart home devices, ensure they’re not constantly syncing or pushing large data.
  1. ISP and external network checks
  • Check outage/maintenance notices in your area (your ISP’s status page or outage maps).
  • Compare your tested speeds to your plan’s advertised rates. If consistently below, note the gap.
  • Try a different gateway mode: bridge mode (if you have a separate modem and router) to rule out router-as-router issues.
  • If problems persist on all devices, contact ISP with your speed test results, times, and logs from tracert/pathping.
  1. Advanced tests and tuning (optional)
  • MTU: incorrect MTU can cause fragmentation; test with: ping -f -l [payload] [destination] (Windows) to find the largest stable size, then adjust MTU accordingly on your router.
  • Latency/Jitter: use continuous ping tests to your router and to external targets (e.g., 8.8.8.8 and your gateway) to measure stability over time.
  • Wireless specifics: test on 2.4 GHz vs 5 GHz, and try different SSIDs if you have a tri-band or separate radios.
  • QoS rules: if you have custom QoS, temporarily disable and test; some QoS settings can throttle or misprioritize traffic.
  • Check for faulty hardware: if a specific router or modem model often shows issues in reviews or forums, consider replacement.
  1. Create a remediation plan and verify
  • Implement the smallest set of changes (e.g., swap a cable, update firmware, change Wi‑Fi channel).
  • Rerun baseline tests after each change to measure impact.
  • Document findings, changes made, and current performance.

When to escalate

  • If wired tests are consistently slower than your plan, or you see persistent high packet loss or jitter that you cannot fix with local changes, contact your ISP with data from tracert/pathping, speed tests, and timestamps.
  • If you suspect faulty hardware (router/modem), test with rental or a known-good device from a friend or service provider, or request a replacement from the ISP.
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