When network emergencies occur, with websites not loading and access issues in applications like QQ, what can you do to troubleshoot before calling your network administrator? This Network Troubleshooting Guide offers practical steps for common network connectivity issues.
1. Network Topology Overview
Description: The operator (China Mobile/China Unicom/China Telecom) connects the optical fiber to the user’s home fiber-to-home information box, connects it to the optical modem port provided by the operator, and then connects it to the WAN port of the wireless router. Finally, the LAN port of the router connects to various devices and sends wireless signals to mobile phones, PADs, etc.
Some optical modems now integrate wireless routing functions, which is equivalent to the original optical modem + router. This article still explains the most basic ones.
2. Troubleshooting Network Issues
2.1. Network Troubleshooting for Optical Modem Issues
Unplug the network cable 1 from the router WAN port and plug it into a normal laptop. If you can access the Internet, the optical modem is out of service. If not, observe the “LOS” and “PON” indicators on the optical modem. Normally, the LOS indicator should be off and the PON indicator should be on. If not or it flashes, contact the operator to resolve the issue.
2.2. Router Network Troubleshooting Steps
If the optical modem is working properly, plug network cable 2 into a normal laptop. If it still does not work, it is a router problem. Please follow the steps below.
Check the router interface to see if the WAN port and LAN port are connected correctly;
(1) To reset the router, press the reset button for more than 10 seconds. You will need to reset the wireless password after resetting.
(2) If you do not have a laptop, you can check whether the network of other devices connected to the router is normal. If not, perform the following operations.
2.3. Network Troubleshooting for Cable Failures
The most effective and intuitive way to troubleshoot network cable failures is to use a cable tester to check whether there are any broken cables. Normally, all 8 cables are straight-through, and there are also low-speed cables with only 1236 cables straight-through. As shown in the figure:
If you don’t have a cable tester, you can use the replacement method. Replace the network cable with a normal one and check whether it works normally.
2.4. Computer failure
If you find that the optical modem, router, and network cable are all normal, but only the computer cannot access the Internet, then it is definitely a computer failure. Generally, there are several reasons:
2.4.1 Network card hardware failure
Find a computer repair company.
2.4.2 Network card driver failure
Open the device manager, and if a question mark is displayed on the network card device, it means that there is a problem with the network card driver, and the specified model of the network card driver needs to be reinstalled. Tips: You can directly download the network card version of Driver Genius, which will come with a universal network card driver after installation.
2.4.3 IP and DNS server settings
Generally, the network connection icon is a yellow exclamation mark. At this time, right-click on the network icon and click Troubleshooting to fix some problems. If it doesn’t work, configure IP and DNS to obtain automatically.
Start → Run → Enter: CMD Click OK (or press Enter) to open the Command Prompt window, enter the following two instructions and press Enter (after the colon).
Automatically obtain IP command: netsh interface ipv4 set address “local connection” dhcp
Automatically obtain DNS command: netsh interface ipv4 set dns “local connection” dhcp
2.4.4 LSP failure (QQ can be accessed but the browser cannot be opened)
Start → Run → Enter: CMD Click OK (or press Enter) to open the Command Prompt window. Enter the following command and press Enter (after the colon).
Reset the Winsock catalog: netsh winsock reset