Packet Loss: How to Diagnose and Fix It in 7 Steps

Choppy voice calls, games that stutter at critical moments, video conferences where everyone sounds like a robot — these are the hallmark symptoms of packet loss. Even a 2% loss rate is enough to make real-time applications feel broken, yet most people never think to check for it when troubleshooting slow internet.

This guide walks you through exactly what packet loss is, how to measure it accurately, and the seven steps most likely to fix it.

What Is Packet Loss?

When data travels across the internet, it's broken into small chunks called packets. Each packet is sent individually and reassembled at the destination. If any packet fails to arrive — due to congestion, hardware faults, or interference — it is considered lost.

The packet loss rate is expressed as a percentage:

> Packet Loss (%) = (Packets Sent − Packets Received) ÷ Packets Sent × 100

For TCP connections (web browsing, file downloads), lost packets are retransmitted automatically, so you notice slowdowns rather than outright failures. For UDP connections (VoIP, gaming, video streaming), there is no retransmission — lost packets simply disappear, causing the glitches and stutters you hear and see.

What Packet Loss Rates Mean in Practice

Step 1: Confirm You Actually Have Packet Loss

Before chasing ghosts, measure the problem. Open a terminal and run a continuous ping to a reliable public server:

Windows:

ping -n 100 8.8.8.8

macOS / Linux:

ping -c 100 8.8.8.8

Look at the summary line. Any value above 0% in the Packet Loss field is worth investigating. For a more detailed picture, use MTR (My Traceroute), which combines ping and traceroute into a live, hop-by-hop loss report:

mtr --report --report-cycles 100 8.8.8.8

You can also use our Network Diagnostic Tool to run a browser-based test without installing software.

Step 2: Identify Where the Loss Is Occurring

MTR output shows loss at each hop between your device and the destination. This is critical: loss at an early hop (low hop count) points to a problem near your home or router, while loss at a later hop suggests an issue with your ISP's backbone or the destination server.

Reading MTR output:

In this example, hop 3 shows 12% loss but hop 4 shows 0%. This is normal — many routers deprioritize ICMP ping responses and artificially appear lossy. If loss appears at an intermediate hop but not at subsequent hops, the packet loss is a measurement artifact, not real data loss.

True packet loss shows up at the final destination hop or persists through all subsequent hops.

Step 3: Eliminate Your Own Hardware

Local hardware fails more often than ISPs admit. Work through this checklist:

• Ethernet cable — Swap the cable between your PC and router. Damaged cables cause intermittent packet loss that is almost impossible to diagnose any other way.
• Switch or hub — If you have a network switch, bypass it and connect directly to the router.
• Router — Reboot the router and modem. If you have a spare, try it. Overheating routers are a common cause of random packet loss.
• Network interface card (NIC) — Update your network adapter drivers. On Windows, open Device Manager → Network Adapters and check for driver warnings.

Step 4: Check Your WiFi Environment

Wireless connections are inherently more lossy than wired ones. If you're on WiFi:

• Move closer to the router. Packet loss increases sharply when signal strength drops below −70 dBm.
• Switch bands. 5 GHz is faster but shorter-range; 2.4 GHz penetrates walls better. Try switching if you're borderline.
• Change the WiFi channel. Neighboring networks on the same channel cause collisions. Use a tool like WiFi Analyzer to find a less congested channel.
• Check for interference. Microwaves, baby monitors, and older cordless phones operate at 2.4 GHz and can cause bursts of packet loss lasting several seconds.

If switching to a wired Ethernet connection eliminates the packet loss entirely, your problem is definitively WiFi-related.

Step 5: Rule Out ISP-Side Congestion

ISPs sometimes oversell their capacity. During peak hours (typically 7–11 PM on weeknights), shared network segments can become congested enough to cause measurable packet loss.

How to test: Run your MTR test at different times — say, 9 AM and 9 PM. If packet loss is significantly worse in the evening, congestion on your ISP's last-mile network is likely. Document these results with timestamps before calling your ISP.

Also check for issues with your cable line if you're on a cable/DOCSIS connection:

• Log into your cable modem's diagnostic page (usually at 192.168.100.1).
• Look for uncorrectable codeword errors or SNR (Signal-to-Noise Ratio) values below 30 dB on downstream channels.
• High uncorrectable errors strongly suggest a physical line problem — loose splitter, damaged coax, or a corroded connector at the street cabinet.

Step 6: Fix Software-Side Causes

Not all packet loss originates in the network. These software issues mimic the symptoms:

• Outdated network drivers — Particularly on Windows, driver bugs can cause the OS to drop packets before they even reach the physical adapter. Update from the manufacturer's website, not Windows Update.
• QoS misconfiguration — Quality of Service settings on your router may be throttling or deprioritizing certain traffic types.
• VPN overhead — VPN encryption adds overhead that can cause fragmentation and packet loss on connections with a low MTU. If you use a VPN, test with it disabled. See our VPN troubleshooting guide for more details.
• Firewall rules — Overly aggressive firewall rules can silently drop packets. Temporarily disable third-party firewalls to rule this out.

Step 7: Contact Your ISP with Evidence

If steps 1–6 haven't resolved the issue, the problem is almost certainly on your ISP's side. When you call, lead with data:

1. MTR reports showing loss at specific hops, with timestamps.
2. Cable modem diagnostics showing uncorrectable errors (if applicable).
3. Time-of-day patterns if the loss is worse during peak hours.

Ask specifically for a line technician visit to check the physical connection from your home to the street. Avoid accepting a remote reset as the only remedy — if you have documentation of signal quality issues, a field visit is warranted.

Quick Reference: Packet Loss Causes by Symptom

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