What should I do if the computer network cable shows that there is no network connection?

There are many reasons for this phenomenon, and the following aspects are also the fundamental reasons. You may wish to check it carefully and comprehensively according to the following aspects; Your problem will be solved.

Copyright statement: this answer is harmonious and original, and no one can steal it! 1: Check the power supply (after the transformation of the two national networks, including remote mountainous areas, the voltage of 99.98 is qualified and there is no low voltage; The low voltage is caused by the thin wire diameter of the user, so it is ok to replace the incoming wire.) 6438+0. 1 Check whether the power supply is stable with a multimeter? 1.2 Is the AC voltage fluctuation within the allowable range? Is the ripple coefficient after 1.3A/D power conversion (checked by millivolt meter) qualified? 1.4 Is the temperature rise of the power supply abnormal? Does the voltage stabilizing characteristic of 1.5 meet the technical index? 1.6 Do the voltage stabilizing characteristics and ripple coefficient meet the technical indicators under rated load? 1.7 When replacing the large fan, does your power supply capacity meet the requirements? 1.8 power supply for general auxiliary equipment (routers, network switches, cats, etc.). ) is a rectifier power supply, with no voltage stabilizing function, large ripple coefficient (possibly due to dry filter capacitor) and poor load capacity; Special attention should be paid. 1.9 Due to overvoltage of equipment (like feeding children, it is more likely to die), low voltage (like feeding children, lack of which will lead to malnutrition), excessive voltage fluctuation (like feeding children, hungry), overcurrent and fever, the overheating protection action will be cut off, and the equipment will not run (that is, it will be slow, delayed and not run)/kloc-0. Are you agile? Refuse to move or misoperation? 2. Check whether the network cable and the crystal head (R45 ): 2. 1 Are the crystal head and socket plugged in (loose)? 2.2 contact? What is the contact resistance? 2.3 Is there dust? Is it oxidized? 2.4 Are the mechanical locks of the crystal head and seat locked? 2.5 Is the locking firm? 2.6 Are the cable and the crystal head pressed tightly and in good contact? 2.7 The insulation resistance between network cables (using 100V shaking table) should be greater than 20 megohms.

Copyright statement: this answer is harmonious and original, and no one can steal it! 3. Lightning protection and grounding: grounding is mainly to ensure the safety of people and equipment! Lightning will burn the network card; In severe cases, it can cause fire and casualties! Multi-point grounding, repeated grounding and nearby grounding are the principles; Grounding is divided into protective grounding, shielding grounding and working grounding. Static electricity is the chief culprit of blue screen of death! I tested with a noise meter, and the noise voltage without grounding is more than 6000 times larger than the signal. Can your equipment work under such high noise if it is not grounded? Grounding is the most basic requirement, especially for analog devices and digital circuits. Grounding can reduce or eliminate interference from all sides, external interference and inter-line coupling between local and local wiring. Do a good job in grounding shielding of equipment. A lot of interference comes from poor shielding and grounding. Many people only do software, and many interferences are caused by poor grounding or no grounding. This kind of fault is very easy to happen and is easily overlooked by many people. Many equipment damages are directly related to grounding. Ungrounding or poor grounding will lead to intersymbol interference, error code, delay, packet loss, interruption, disconnection (disconnection, interruption), crash, jamming, automatic shutdown, repeated startup, repeated restart (or repeated connection) and other phenomena. Grounding must have more than two grounding electrodes, and the interval between each grounding electrode should be at least10m. There should be no joint between the grounding electrode and the grounding wire of the machine room. Soft copper wire with a cross section of not less than 25mm2 should be introduced into the bus bar of the machine room (no joint is allowed in the middle). The grounding wire should be symmetrically connected with Faraday net to facilitate shunt and scattering. The connection point with the bus should be coated with silver powder conductive paste, and the cross section of the grounding wire from each device to the bus (independent) should not be less than 4m2.

Check the grounding instrument at least twice a year (measured with a grounding instrument of class 2.5 or above, and the instrument is in the inspection period). When checking the grounding electrode, it is strictly prohibited to do it in thunderstorm weather.

It is forbidden to use the N zero line of water pipes and power lines as grounding; I.e. an independent grounding device. The wires of each equipment are independently connected to the bus bar of the machine room, and it is forbidden to connect the bus bar after series connection.

I can say subjectively: whether you are an individual user or a collective user of a large computer room, you are not grounded at all (or the grounding gas is unqualified). Copyright statement: this answer is harmonious and original, and no one can steal it! 4. Bandwidth: The bandwidth from operators to users is very important. Without enough bandwidth, enough data traffic cannot be guaranteed; Computers can't surf the Internet smoothly; The bandwidth mentioned above refers to the bandwidth of the whole journey, which is as wide as that on the expressway, and there can be no ups and downs in the whole journey; A slight fluctuation in the whole process will affect the network speed; Users have the right to ask operators (tested with frequency scanners) to give protection; 5. Signal-to-clutter ratio: (Signal-to-noise ratio can be understood as signal purity) When the signal is small, the useful signal is covered by noisy stray signals (especially intersymbol interference between symbols), which makes the receiving path unable to correctly extract the useful signal from the noisy signal, and the decision circuit cannot correctly judge the symbols, which will lead to error code and serious error code loss, which is the reason for the delay. Serious delay will mean disconnection (which will cause slowness, delay, repeated startup, disconnection, delay, disconnection, interruption, disconnection, automatic shutdown, collapse, etc.). ). Use a noise meter or level meter to measure whether the noise level is within the allowable range, or use an oscilloscope to observe whether there are stray signals? Is there intersymbol interference? Take measures to eliminate.

Signal-to-clutter ratio is also greater than 60dB. Test (observe) with frequency scanner and oscilloscope.

This indicator is to ensure smooth roads. With such a wide road, the whole journey is barrier-free.

6. Matching: Matching includes level matching and impedance matching (tested by level meter and signal generator). 6. 1 level matching: the received signal cannot be too low. If it is too low, it will not reach the threshold level amplitude required by the receiving path, and the equipment will not work normally; .

2. The computer network cable is connected, but the display is not connected. What should I do?

This is caused by the following reasons:

First of all, the computer itself, network card problems, drive shutdown, or network cable problems, routers and other reasons can not access the Internet, one by one to rule out.

Second, there is a virus in the computer, IE has been maliciously modified, and IE has made an error. Can be disinfected and repaired with Huangshan IE.

Third, the data packet is lost, which may be a problem with the crystal head. Redo the crystal head.

Fourth, the route does not turn on DHCP, so IP cannot be obtained, the network is limited, or someone in the same network uses executive to cause interference.

Fifth, the network speed is slow, which may be poisoning, or someone on the same network seriously occupies resources, such as BT, downloading.

6. QQ and other instant messaging software can log in, or open the webpage. Perhaps DNS is not set, please set it according to the local public DNS address.

7. Unable to access the Internet due to system damage, please reinstall or restore the system.

Eight, even after surfing the internet, I just can't open the webpage. There may be something wrong with the network signal. Please contact the local broadband access department for inspection.

Router, if the cat is overheated, please turn off the power for fifteen minutes and try again.

3. Why do you plug in the network cable computer or show that the network connection is unknown?

1) If it is a broadband problem, directly connect the broadband network cable for testing. If it is a broadband problem, contact broadband customer service to solve it.

2) If it's a router problem, if it worked before, it won't work for the time being. My own way is to disconnect the power of the router and plug it in. See you later. If it can be restored to the factory settings, it can be used in strict accordance with the instructions. You don't understand, so it is not recommended to set it at will (this is sometimes caused by the slow or failed IP address search of the router under the premise of correct physical connection, not the router is broken).

If I can't solve it all the time, I suggest calling the customer service of the router. They have telephone online guidance. If I encounter problems that I can't solve, it is very useful to ask their advice. They will provide correct advice for your setup or operation.

3) If the wireless switch is off, just turn it on. If it is a software wireless connection, the software is not easy to use, and it is normal to have problems frequently. There is no better way to use a router. In addition, the network card driver is not suitable or not suitable, and there is something wrong with the network cable interface or network cable.

4) If it is caused by system problems, it is recommended to restore the system or reinstall it.

4. The network cable is normal, but the computer does not display broadband connection. How can I connect to the wireless network by myself every time?

Broadband connection is an online program that computer systems will integrate. It's not that there is no monitor, but there is no broadband connection, and there is no shortcut on the desktop.

Win7 creation method:

Step 1: Click Start-Control Panel-Network and * * * Enjoy Center, and click "Set up a new network or connection" below.

Step 2: Click and select "Connect International".

Step 3: Click and select "PPPoE (R)".

Step 4: Enter the broadband account number and password in the user name and password, and check the check box before "Remember this password".

Step 5: Go back to the "Network and * * * Enjoy Center" at the beginning of setup, and click "Change Adapter Settings" on the left.

Step 6: Right-click the created broadband connection and select Create Shortcut. At this point, you will be prompted that you cannot create a shortcut in the current location. Do you want to put the shortcut on the desktop? The point is.

At this point, the desktop will create a shortcut to broadband connection.

5. The computer plugged in the network cable shows that there is no network access to the unidentified network.

If the broadband connection prompt does not recognize the network, you can do the following:

1. Open the computer control panel, click Network Connection, select Local Area Connection, right-click the Local Area Connection icon, and then select Properties. In the general tab, double-click Inter Protocol (TCP/IP), select the following IP address, and fill in "192" 40616.66666666666. Note that IP must be in the same network segment as the IP address of the modem.

2. In addition, in the above steps, the option "Notify me when this connection is restricted or disconnected" can be deleted from the Properties of Local Connection.

6. The network cable is ok and can be connected, but the computer shows that there is no network.

It is probably due to the system. If the driver is not installed or the driver is wrong, this prompt will not be given.

Please refer to this link:

The following is the solution on the network, which is copied to you:

WIN7 Ultimate System prompts to solve the unrecognized internetwork:

1. For the setting of opening local connection, except for the IPv4 protocol, the third-party firewall protocol installed by yourself (if you have a third-party firewall) and the QoS protocol (it is recommended not to tick because some people think the network speed is fast), all other protocols in Win7 system should be unchecked and cancelled. Then click IPv4, select properties, and configure the IP address:192.168.1.2, subnet mask: 255.255.0, gateway:192.5438+068.6438+0. Then click on the details, and you can see that there are two IPv4DNS (dial-up users, IP addresses are randomly assigned, but this DNS is fixed). Copy it and fill in the local connection.

Here is one. The first one is192.168.438+0.6438+0. Ok, connect locally here, and click OK.

2, broadband connection, properties, network, only check the IPv4 protocol, other cancel.

3. Open IE, enter the inter option, connect that item, set up the local area network, click in, then cancel the automatic detection setting option, and confirm that all settings here are complete.

4. Finally, return to the "Network and * * * Enjoy Center", right-click the icon of local connection, click the network in the pop-up window, and then click the merged network below. You will find that the "unknown network" is gone and the problem is solved.

Unknown network is also a common problem. In this case, the network cannot be used normally. If the user encounters the same failure problem, try the solution in the tutorial.

The WIN7 Ultimate system prompts that several services are set to manual or disabled because the network is not recognized. Among them: IPHELPer, workConnections and RemoteAccessConnectionManager. These services cannot be disabled and must be set to start automatically.

7. After the desktop computer network cable is connected, it shows that it is not connected. What should I do?

If the network cable problem is eliminated, it can be solved by the following methods.

1, right-click Network-Properties.

2. Click on the left column to change the network settings.

3. Open-Right-click Local Area Connection after it is enabled.

Description:

1. If the network card driver is lost, you need to install the network card driver.

2. If the network itself is not working, you need to ask the operator to detect or even change the line.

8. What if the computer can't connect to the network and the network is not recognized?

Methods/steps

When we can't identify the network and the network connection is unavailable, the display is like this.

First, let's see if the network is disabled. Open the network and enjoy the center, as shown in the figure:

Then, select Change Adapter Settings, as shown:

Then, enable the disabled network connection.

Right-click the mouse and select the enabled item.

We can also try to update the driver of the network card and update it in a way that can access the Internet.

For example, if you can't identify the wireless network, you can update the driver of the wireless network card through wired connection, and then see if it is solved.

We can also check whether there is something wrong with the network cable and whether there is a wifi signal nearby.

You can search whether there is a wifi signal nearby by checking whether the network cable is plugged in and damaged.

We can also try to solve this problem by setting ip and dns server addresses.