Most electronic equipment used in a home or business network has built-in software to run the device. This software is usually referred as firmware. Computers, Smart TVs, and streaming devices like Roku, and Amazon Fire sticks will prompt a user to upgrade the firmware(software) when that device has an Internet connection. The firmware upgrade will correct any known issues that a previous version had and possible add additional features to the device.
For most wireless routers, this firmware upgrade prompt is not automatically. A user will have to manually update the firmware on the wireless router.
You will have to check with your router vendor’s website on how to upgrade your router.
Here is a link to firmware downloads or router support.
Linksys/Cisco: http://www.linksys.com/us/support-article?articleNum=164513 
DLink: http://support.dlink.com/ 
A Google search for your router model number can also be helpful in finding vendor information.
Importance of Router Firmware Updates
A customer has this router.
Accessing the router management page from a LAN computer shows the current firmware version. Noticed this router’s firmware was released in 2009. At the time of this article, that made the firmware 6 years old.
Cisco’s firmware release notes (see graphic) for this model shows 4 additional firmware versions have been released since version 1.0.04 and one of those versions fixed an issue this router had been experiencing: “Resolve some DHCP lease issues”. Also, note that no additional firmware versions have been released since 2012 which is 3 years ago at the time of this writing. This gap of having updates usually indicates that the vendor will not have additional releases for this older router.