PH
PriceTag HUB
PriceTag HUB / Networking

Computer Networking

Learn computer networks, Wi-Fi, routers, IP addressing, network protocols, troubleshooting, and network security through practical guides and step-by-step explanations.

Practical Network Troubleshooting

Network Troubleshooting Tools & Commands

Internet not working? Wi-Fi disconnecting? DNS errors or packet loss? Find the likely causes, run the right diagnostic commands, and follow practical steps to investigate your network problem.

Find Your ProblemView Commands
Beginner-friendly explanationsWindows diagnostic commandsStep-by-step investigation

NETWORK DIAGNOSTICS

Follow the connection

Your device

IP address and adapter

Wi-Fi / Router

Local gateway reachability

DNS resolver

Domain name resolution

Internet service

Remote host and application

Diagnostic tip: Start with your local gateway, then test an external IP address and DNS. Compare results instead of guessing at the cause.

Advertisement

Common problems

Symptoms, causes, and solutions

Troubleshooting steps

Follow a logical diagnostic process

Command reference

Useful commands and explanations

Safety notes

Understand commands before using them

Problem-solving library

What network problem are you facing?

Choose the symptom that best matches your situation. Each guide explains common causes, commands to run, and practical next steps. These checks help narrow down the cause; they do not guarantee a single diagnosis.

PROBLEM 01

Connected to Wi-Fi but no internet

Wi-Fi shows connected, but websites do not load.

Possible causes

  • Router has lost its internet connection.
  • Device has an invalid IP configuration.
  • DNS resolution is failing.
  • The ISP is experiencing an outage.

Commands to investigate

ipconfig

Inspect the device's IP address, gateway, and adapter configuration.

ping 192.168.1.1

Test connectivity to your router. Replace the address with your actual default gateway.

ping 1.1.1.1

Test connectivity to a public IP address.

nslookup example.com

Check whether a DNS server can resolve a domain name.

Step-by-step solutions

  1. 1Check whether other devices can access the internet.
  2. 2Restart the router if you are authorized to manage it.
  3. 3Run ipconfig /all and check the default gateway and DNS server.
  4. 4If the gateway is unreachable, investigate Wi-Fi connectivity, the adapter, or router.
  5. 5If public IP connectivity works but domain names fail, investigate DNS settings.

PROBLEM 02

Slow internet or slow Wi-Fi

Pages take a long time to open, downloads are slow, or video buffers.

Possible causes

  • Weak Wi-Fi signal or radio interference.
  • Network congestion or heavy background downloads.
  • An overloaded router or access point.
  • ISP congestion or a slow internet plan.

Commands to investigate

ping -n 20 1.1.1.1

Measure response times and packet loss over 20 probes on Windows.

tracert 1.1.1.1

Inspect the route toward a public IP address.

netstat -e

Display Ethernet statistics, including received and transmitted errors.

Step-by-step solutions

  1. 1Run a speed test near the router and compare it with a wired connection.
  2. 2Move closer to the access point and reduce physical obstructions.
  3. 3Pause large downloads and check whether performance improves.
  4. 4Repeat the test at different times to identify congestion.
  5. 5Contact your ISP if repeated tests show a problem beyond your local network.

PROBLEM 03

DNS server not responding

Websites fail to resolve by name, even though the network appears connected.

Possible causes

  • DNS server is unavailable or unreachable.
  • Incorrect DNS configuration.
  • Temporary resolver or DNS cache problems.
  • Firewall or network policy interference.

Commands to investigate

nslookup example.com

Test domain resolution using the configured DNS server.

ipconfig /all

Identify the DNS servers configured for the adapter.

ipconfig /flushdns

Clear the local Windows DNS resolver cache.

Step-by-step solutions

  1. 1Check whether the configured DNS server is reachable.
  2. 2Try resolving more than one domain to determine whether the failure is widespread.
  3. 3Flush the DNS cache if stale local records are suspected.
  4. 4If appropriate, use a trusted DNS resolver approved by your network administrator.
  5. 5On managed networks, do not replace internal DNS settings without authorization.

PROBLEM 04

IP address conflict or invalid IP

Windows reports an IP conflict, or the device cannot communicate with local systems.

Possible causes

  • Two devices are using the same manually configured IP address.
  • DHCP server is unavailable.
  • Incorrect subnet mask, gateway, or static configuration.
  • The adapter has received an APIPA address beginning with 169.254.

Commands to investigate

ipconfig /all

Inspect IPv4, subnet mask, DHCP status, and default gateway.

ipconfig /release

Release the current DHCP-assigned IPv4 lease.

ipconfig /renew

Request a new DHCP lease.

arp -a

Inspect the local ARP cache for IPv4-to-MAC address mappings.

Step-by-step solutions

  1. 1Check whether the adapter has a valid address for the local subnet.
  2. 2Confirm that DHCP is enabled if the network uses automatic addressing.
  3. 3Use ipconfig /release and ipconfig /renew only on a suitable DHCP-configured adapter.
  4. 4Ask the network administrator to investigate duplicate static addresses or DHCP scope exhaustion.

PROBLEM 05

Packet loss or unstable connection

Video calls freeze, games disconnect, or connections repeatedly time out.

Possible causes

  • Weak wireless signal or interference.
  • Faulty Ethernet cable or network adapter.
  • Congested network equipment.
  • Problems along the route to a remote destination.

Commands to investigate

ping -n 50 192.168.1.1

Test packet loss and latency to your actual local gateway.

ping -n 50 1.1.1.1

Compare local connectivity with a public destination.

pathping 1.1.1.1

Analyze latency and packet loss across a route. Results may take several minutes.

Step-by-step solutions

  1. 1Compare local gateway tests with remote destination tests.
  2. 2If loss occurs to the gateway, investigate the local Wi-Fi or wired link.
  3. 3Repeat tests at different times and against more than one destination.
  4. 4Use a known-good cable or wired connection to isolate wireless issues.
  5. 5Do not conclude that a single intermediate router is faulty just because it does not answer probes.

PROBLEM 06

Websites or services are unreachable

Some websites or servers fail while other internet services continue working.

Possible causes

  • DNS resolution failure.
  • Remote service outage.
  • Routing problems.
  • Firewall, proxy, or port restrictions.

Commands to investigate

nslookup example.com

Check whether the destination hostname resolves.

tracert example.com

Inspect the network path toward the destination.

Test-NetConnection example.com -Port 443

Test TCP connectivity to HTTPS on Windows PowerShell.

netstat -ano

Inspect active connections and listening ports on the local computer.

Step-by-step solutions

  1. 1Determine whether the issue affects one domain or many domains.
  2. 2Check the service status using its official status page when available.
  3. 3Test the relevant TCP port using PowerShell.
  4. 4Review proxy and firewall settings if a connection is blocked.
  5. 5Escalate suspected remote routing or ISP issues with timestamps and diagnostic results.

PROBLEM 07

Wi-Fi keeps disconnecting

The wireless connection drops repeatedly or reconnects by itself.

Possible causes

  • Weak signal, interference, or channel congestion.
  • Outdated or unstable wireless drivers.
  • Router firmware or access-point problems.
  • Power-saving behavior or roaming between access points.

Commands to investigate

netsh wlan show interfaces

Inspect wireless state, SSID, signal information, and radio details.

netsh wlan show drivers

Display wireless adapter and driver information.

netsh wlan show wlanreport

Generate a Windows wireless troubleshooting report.

Step-by-step solutions

  1. 1Check signal strength and test near the router.
  2. 2Update the wireless driver using the computer manufacturer's official source.
  3. 3Install router firmware updates according to the manufacturer's instructions.
  4. 4Inspect the Windows WLAN report for disconnect times and recorded errors.
  5. 5Test another access point to distinguish device problems from router problems.

PROBLEM 08

High latency or connection timeouts

Remote desktop sessions lag, calls are delayed, or applications time out.

Possible causes

  • Network congestion or overloaded uplinks.
  • Long physical distance to the remote service.
  • Wi-Fi interference.
  • A slow or overloaded destination service.

Commands to investigate

ping -n 20 1.1.1.1

Measure round-trip response times and packet loss.

tracert 1.1.1.1

Examine the route and approximate hop-by-hop response times.

pathping 1.1.1.1

Collect route and packet-loss information over time.

Step-by-step solutions

  1. 1Compare idle network performance with performance during heavy usage.
  2. 2Test using Ethernet to isolate wireless issues.
  3. 3Compare results with another public destination.
  4. 4Record repeated measurements before reporting a suspected network problem.
  5. 5Remember that high latency at a single hop can reflect rate limiting rather than actual forwarding delay.
Advertisement

A repeatable method

How to troubleshoot a network systematically

Work from the device outward. Testing each layer helps you avoid changing router, DNS, or firewall settings before you have evidence of the actual problem.

01

Check the physical connection

Verify power, cables, Wi-Fi signal, adapter status, and router indicators.

Continue to next check
02

Inspect IP configuration

Run ipconfig /all and identify the device address, default gateway, and DNS server.

Continue to next check
03

Test the local gateway

Ping your default gateway. If this fails, investigate the local link or gateway.

Continue to next check
04

Test external connectivity

Ping a public IP address and compare results with your local gateway test.

Continue to next check
05

Check DNS and routing

Use nslookup, tracert, or Test-NetConnection according to the observed failure.

Continue to next check
06

Document and resolve

Record timestamps, error messages, and test results before changing configurations.

Example: identify where connectivity fails

If the device cannot reach its default gateway, investigate the local network first. If the gateway responds but an external IP does not, investigate routing or internet access. If the external IP responds but a hostname fails to resolve, investigate DNS. These are diagnostic clues, not absolute rules: ICMP filtering and remote service policies can affect the results.

Windows command reference

Essential network diagnostic commands

Open Command Prompt or PowerShell, enter a command, and read its output. The examples use Windows syntax unless specifically stated. Replace example domains and gateway addresses with appropriate values for your network.

IP configuration

Inspect or refresh network addressing.

ipconfig

Show basic IP configuration.

ipconfig /all

Show detailed adapter, DHCP, DNS, and gateway information.

ipconfig /flushdns

Clear the Windows DNS resolver cache.

ipconfig /renew

Request a DHCP lease renewal.

Connectivity tests

Check reachability and routing.

ping 192.168.1.1

Test your actual local gateway.

ping -n 20 1.1.1.1

Send 20 probes to a public IP address.

tracert example.com

Inspect the route to a hostname.

pathping example.com

Analyze route latency and packet loss.

DNS and ports

Investigate name resolution and TCP connectivity.

nslookup example.com

Query DNS for a domain.

Test-NetConnection example.com -Port 443

Test TCP connectivity to HTTPS in PowerShell.

netstat -ano

Show connections, listening ports, and associated process IDs.

arp -a

Show cached local IP-to-MAC mappings.

Wireless diagnostics

Collect Wi-Fi state and driver information.

netsh wlan show interfaces

Inspect the current wireless connection.

netsh wlan show drivers

Inspect wireless driver capabilities.

netsh wlan show networks

List visible wireless networks.

netsh wlan show wlanreport

Generate a wireless diagnostic report.

Before running network commands

  • • Use your actual gateway address; 192.168.1.1 is only an example.
  • • Run Test-NetConnection in PowerShell, not the standard Command Prompt.
  • • Avoid resetting the entire network stack or changing firewall settings before collecting diagnostic evidence.
  • • Commands that release a DHCP lease may temporarily interrupt connectivity.
  • • Run tests only on systems and networks you own or are authorized to troubleshoot.

Build your networking knowledge

Learn the concepts behind the commands

Troubleshooting becomes easier when you understand how addressing, DNS, routing, and network security work together.

IP Addressing

Understand IP addresses, subnets, gateways, and DHCP.

Explore topic

Firewalls and IPS

Learn how traffic filtering and intrusion prevention affect network connections.

Explore topic

Intrusion Detection

Discover how monitoring systems identify suspicious network activity.

Explore topic

Frequently asked questions

Network troubleshooting FAQs

Quick answers to common questions about diagnostic commands and network problems.

What is the first command to run when the internet stops working?

On Windows, start with ipconfig /all to inspect the network adapter, IP address, default gateway, and DNS configuration. Then test the local gateway with ping using the actual gateway address shown by ipconfig.

What is the difference between ping and tracert?

Ping tests whether a destination responds to ICMP echo requests and reports round-trip times and packet loss. Tracert attempts to show the route toward a destination by using increasing IP time-to-live values.

Why can ping fail even when the internet works?

A destination or firewall may block or rate-limit ICMP traffic. A failed ping alone does not prove that the destination or internet connection is unavailable. Test the actual service or TCP port as well.

How can I diagnose a DNS problem?

Run nslookup example.com and inspect the DNS server being used. Compare resolution of more than one hostname. If name resolution fails but other IP connectivity tests succeed, investigate DNS configuration and reachability.

Are these network commands safe to run?

Most commands shown here are diagnostic and do not intentionally change network configuration. Commands such as ipconfig /release, ipconfig /renew, and ipconfig /flushdns do change local network state or cache contents. Use administrative access only when needed and follow organizational policy.

Can these commands identify every network problem?

No. Command-line diagnostics provide evidence, not a complete diagnosis. Some issues require router logs, firewall logs, packet captures, switch telemetry, ISP investigation, or application-level tests.

Advertisement

Continue Learning

Explore More About Networking Tools

Continue exploring related guides to build your understanding step by step.

Network ToolsNmapWireShark