Good morning. My name is ***** ***** I would be happy to assist you.
These routers have updateable firmware. Have you performed any firmware updates or modified any other settings on the router recently?
Also, could you please provide me the exact model number of your router?
Another possibility to consider, depending on the environment your router is in... These can generate a fairly significant amount of heat. If your router is tucked into a tight place where it can't receive adequate ventilation, it can cause it to overheat. If / when that happens, it may enter a lower power mode in order to protect itself from thermal damage. If the unit has not been moved recently, and this behavior began without any such changes, then that is not likely to be the cause.
One final DIY option you have here (as I see you have already power-cycled the unit), is to log into the router's administrative tool and do a factory reset. To do that, you use your web browser to access your router's administration page (you will need the username and password, which are default values, unless you have changed them.) Alternately, if you are not comfortable doing that, or don't have the administrator name / password, you can usually do a hardware reset, which involves unplugging the router, and depressing a small "reset" button on the unit. Please note that if you do a factor reset, all of the router's settings will be cleared. You should only do this once you are sure that you have any necessary information required to set it back up. Most of the time, these are "plug-and-play". That is, you simply turn it on and it connects. However, if you have wireless devices connected, you will need to know how to set them back up again. You may also have to re-enable WPS on the router after a factory reset if you use WPS to connect your devices.
Alternately, I can connect to your computer and router with you remotely. This would involve you having to perform some steps yourself, but I would be on the phone with you to guide you through the process. There would be an addition charge for this service, however. As I do not see you responding here in the thread, I am going to give you some time to try some of these options and consider your next steps. I will be happy to answer any questions you may have.
If any of these solutions work to resolve your problem, please be sure to hit "Accept answer".