For example, I will use TRENDnet TEW-651BR with firmware 2.00nb03.
I will describe the steps in steps:
1) Download the new firmware from the official site
At the time of this writing, I downloaded version 2.05B01.
2) Open the router settings by typing in the browser the address 192.168.10.1 and enter the standard login – admin, the password – admin.
3) In the interface that opens, click “Tools” – “Firmware”. In the window that opens, click “Browse” and select the previously downloaded firmware file unpacked from the archive, then click “Upgrade” to start the upgrade process.
Wait until the update is complete, usually 2-5 minutes. At the end, the router will reboot.
Is done. After the firmware settings remained unchanged.
I updated the firmware remotely via the WAN port.