Overview
If one computer cannot reach the internet while another computer on the same network works normally, the problem is usually local to the affected computer, its Wi-Fi or Ethernet connection, its network settings, its browser, or its security software. Start by proving whether the failure affects the entire computer or only one application before changing network equipment.
Why this happens
A computer can appear connected while using the wrong wireless network, a failed network adapter, an invalid IP configuration, a bad DNS response, a proxy setting, a VPN connection, or a browser-specific configuration. Comparing the affected computer with a working computer helps isolate the failing layer without disrupting everyone else.
Before you begin
- Confirm that at least one other computer on the same office network can open multiple websites.
- Record the affected computer name, the network it is connected to, and any error message shown.
- If the computer contains unsaved work, save it before restarting applications or the device.
- Do not change router, firewall, DNS, or managed security settings unless you are authorized to do so.
Click-by-click troubleshooting
Step 1: Confirm whether the entire computer is offline
Action: On the affected computer, open the browser and try two unrelated websites. Then open another internet-dependent application, such as Outlook, Teams, or another approved business application.
Why this matters: If only one website or application fails, the computer still has internet access and the problem should be investigated at the application or service layer instead of the network layer.
What to look for: Note whether every internet-dependent application fails, only the browser fails, or only one website or service fails.
Expected result: You should be able to classify the problem as device-wide or application-specific before continuing.
Step 2: Verify the active network connection
Action: In Windows, select the network icon on the taskbar. Confirm that Wi-Fi or Ethernet shows Connected and that the computer is connected to the expected business network. If Wi-Fi is being used, select the network name and verify it is the correct SSID.
Why this matters: A computer can be connected to a guest network, hotspot, disconnected Ethernet adapter, or another network that does not provide the same access as the normal business network.
What to look for: Look for No internet, Action needed, a guest SSID, a disconnected Ethernet connection, or an unexpected network name.
Expected result: The affected computer should show a normal connection to the same network used by the working computer.
Step 3: Compare the IP configuration with a working computer
Action: On both computers, open Command Prompt and run ipconfig. Compare the IPv4 address, subnet, default gateway, and whether the affected computer has an address beginning with 169.254.
Why this matters: An address beginning with 169.254 usually means Windows did not receive a usable address from DHCP. A missing default gateway also prevents normal internet access.
What to look for: The affected computer should have an address in the same expected network range as the working computer and should have a default gateway.
Expected result: If the addressing is valid, continue to test reachability. If it is not, stop before manually assigning an address unless IT directs you to do so.
Step 4: Test the gateway and internet reachability
Action: In Command Prompt, run ping followed by the default gateway address shown by ipconfig. If the gateway responds, run ping 1.1.1.1.
Why this matters: Reaching the gateway proves the computer can communicate with the local network. Reaching an external IP address helps separate general internet connectivity from DNS name-resolution problems.
What to look for: If the gateway fails, focus on the local adapter or network connection. If the gateway works but the external IP fails, the problem is farther upstream or controlled by a security policy.
Expected result: A healthy connection should normally reach both the local gateway and an external IP address, unless ping is intentionally blocked by policy.
Step 5: Test DNS name resolution
Action: In Command Prompt, run nslookup www.microsoft.com. Compare the response with the working computer.
Why this matters: If external IP connectivity works but names do not resolve, the internet connection itself may be healthy and DNS is the more likely failure point.
What to look for: Look for a returned IP address, a DNS server address, timeout messages, or a server-failed response.
Expected result: A working DNS configuration should return one or more addresses for the test name.
Step 6: Check Windows proxy and VPN state
Action: Open Settings > Network & internet > Proxy. Confirm that a manual proxy is not enabled unless your organization requires one. Then check whether an approved VPN is connected and disconnect or reconnect it only if your organization permits that test.
Why this matters: A stale proxy or VPN tunnel can route traffic incorrectly even when the local network connection is healthy.
What to look for: Look for an unexpected manual proxy, a VPN stuck connecting, or internet access returning when an authorized VPN test changes state.
Expected result: The computer should use only the proxy and VPN configuration approved for the organization.
Step 7: Reset only the local connection before escalating
Action: If the earlier checks point to the affected computer, turn Wi-Fi off and back on, or disconnect and reconnect Ethernet. If the issue remains, restart the computer once. Do not reset the office router or firewall.
Why this matters: Reinitializing only the affected device is low risk and can clear a stalled adapter or temporary network stack condition without disrupting other users.
What to look for: Confirm whether the computer receives a valid address and internet access after reconnecting or restarting.
Expected result: If the device still fails while another computer on the same network works, you now have enough evidence for focused IT escalation.
What to look for
- A 169.254 address or missing default gateway points toward DHCP or adapter trouble.
- Gateway works but external IP fails points beyond the local device connection.
- External IP works but names fail points toward DNS.
- Only one browser or application fails points toward that application rather than the whole network.
- An unexpected proxy, VPN, or guest network can explain why only one computer is affected.
When to stop
When to contact IT
Contact IT if the computer repeatedly receives an invalid IP configuration, cannot reach the local gateway, shows security or certificate warnings, requires administrator changes, or remains offline after the low-risk checks above. Provide the computer name, network name, ipconfig results, DNS test result, and the exact error message.
Need help with this issue?
J3 Systems Group supports small businesses and nonprofits with Microsoft 365, Google Workspace, cybersecurity, devices, documentation, and day-to-day IT operations.
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