Method 1: indicator check
First of all, we recommend to learn about the availability of the network, even if the indicator on the router does not burn. The situation that has arisen may be caused by software problems or banal failure of the bulb itself responsible for the visibility of the Internet cable. If you manage to connect to the Internet, it means that the problem is in the device, not a network wire.
You can try to update the firmware if there are suspicions that the indicator is not lit due to program reasons, however, this situation is solved by replacing the indicator in the service center or the purchase of new network equipment. It is possible to leave it at all as it is, because there are no functional restrictions the lack of light bulb.
If none of the above methods have not been useful, boldly contact the technical support of the provider and check if the technical works are being conducted, since they may also cause the situation under consideration. Additionally, employees can clarify other methods of solving or ask them to independently check access to the network on your line.