High Latency and Packet Loss

Problem

A connection works but is slow or unreliable, with high ping times or dropped packets.

Symptoms

• Video calls freeze or garble audio
• File transfers are slow or stall
• ping shows request timed out for some packets, or unusually high response times

Possible Causes

• Wi-Fi interference or weak signal
• Network congestion (too much traffic for available bandwidth)
• A failing cable, port, or intermediate hop
• ISP-side congestion or an outage in progress
• A misbehaving device flooding the local network

Diagnostic Steps

1. Run an extended ping test to observe patterns, not just a single result
2. Run a traceroute to find exactly which hop introduces the delay or loss
3. Test on wired vs. wireless to isolate Wi-Fi specifically
4. Check for bandwidth-heavy activity elsewhere on the network

Commands & Tools

Step-by-Step Solution

1. If loss appears at the first hop, the local network (Wi-Fi/cable) is the cause
2. If loss appears several hops in, it's likely ISP or upstream, not local
3. Move closer to the access point or switch to 5GHz/wired if Wi-Fi interference is suspected
4. Identify and pause any bandwidth-heavy process (large downloads, backups) competing for capacity
5. Replace suspect cables and test a different switch port

Verification

Extended ping shows consistent low latency with 0% loss, and the original symptom (video call quality, transfer speed) is resolved.

Common Mistakes

• Drawing conclusions from a single ping instead of an extended test
• Not running traceroute to actually localize where the loss occurs
• Blaming the ISP without first ruling out local Wi-Fi interference

Escalation Criteria

Prevention

Use wired connections for latency-sensitive work where possible, monitor for interference sources near access points, and set bandwidth policies for heavy background traffic.

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