Troubleshooting the red LOS light on the router

LOS is the name of a technology that exists in routers from different manufacturers. Sometimes it is not supported or the developers have simply decided not to implement it, using PON instead. The following instructions are also suitable for these models, as the fixing methods are universal.

Method 1: Check the Internet Cable Connection

A LOS light on on the router in most cases means that the device cannot see the network cable, consequently there will be no internet access because the signal from the ISP is simply not getting through. In this situation, you do not have to interact with the configuration of the computer or the router, but you have to pay attention to the hardware itself and the connected cables. Start with the WAN cable that comes from the ISP and is connected to the interface with the same name on the device itself. Make sure the cable itself is properly seated in the port and has no visible physical damage. It is important to observe its entire length and correct any kinks, if any, as even a small bend can cause signaling problems.

Also, try tightening the cable into the connector or unplugging it several times and plugging it back in, checking how the router's indicators respond. If you use an electrical outlet, make sure it is in good condition. If these actions are unsuccessful, go to the next method.

Method 2: Check the plug

The Internet cable almost always connects to the router's WAN or ADSL port, which depends on the type of connection provided by your Internet service provider. The connector itself can also cause the LOS or PON light to come on, for example when it is malfunctioning or dust has gotten into it.

Inspect the connector yourself for damage, making sure all the pins are in place. Use a dry cloth or rod to remove any debris that may have gotten into the port. After that, reconnect the power cord and check how the LED now behaves.

Method 3: Check the rate

Almost all providers give their users access to a personal account in which you can carry out any action with your rate plan and control the status of your network. The LOS light may have come on because you simply forgot to pay your internet bill and your service provider has temporarily restricted your network access, causing the problem. Access your personal cabinet, know the status of your connection and recharge your account if necessary. To solve all the problems that have arisen during the use of the services of the provider, contact the technical service by finding out their contacts on the official website of the company.

Method 4: Check the Internet Cable

This option only applies to users who live in a private address. In this type of connection, the ISP passes the network cable through the cables of the electrical or underground line, leading them to the house for later connection. Sometimes the cables are not sufficiently protected and insulated, so they can be affected by external factors such as weather conditions or an accidentally fallen tree. If the cable is on the surface and most of it goes directly to the yard, visually inspect for physical damage. If you find any, contact your Internet Service Provider to clarify the situation.

Sometimes the ISP itself does the repairs for line damage. Then the Internet will also turn off and the LOS light will turn on. You can call technical service to find out if it is being worked on. Also, they can tell you what to do to resolve the situation.

Method 5: Check the connection to the splitter

This option refers to ADSL technology, when the ISP activates a domestic telephone, through whose line the Internet is provided. With this type of connection, a small device - a splitter - is always installed in your apartment or house. There you connect the cable from the ISP and the phone, and then it is brought to the WAN to the router. Make sure all cables are connected properly and securely, and inspect for damage.

Method 6: Check your home phone

As you can understand, this method is also related to ADSL users. There is also a cable connected to the phone, which is responsible for the network signal. If it is suddenly disconnected or broken, the LOS light may turn on, so find this wire and inspect it in the same way as described in all other methods.

Method 7: Reassign the network port

In closing, let's consider a method that is only relevant to a small percentage of users, as only a few network equipment developers implement these features on their devices. This technology implies the possibility of connecting a WAN cable to any LAN port and normally receive the signal from the provider, but for this it is necessary to make some changes in the web interface. If you have a ZyXEL router, do the following, checking the port and, if necessary, reassigning it to exclude the possibility of failure.

1. Please log in to the Internet Center as indicated in the separate instructions at the link below.

Read more: Access the web interface of the Zyxel Keenetic router

2. Go to the network settings and specify your connection option, then open the profile for editing.
3. On the line. "ISP Cable." select the connector you want to use. You can even check each of them, waiting to see if the LOS light comes on this time.

If none of this helps, the router or cables are likely physically broken, other than that don't rule out a problem on the ISP side. In either case, you will need to contact technical support to further resolve the issue.

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