USB to UART Module
If you ever bricked your modem or router, one possible way to revive it is to use a UART (TTL Serial) connection to communicate with the onboard serial port directly.
We have several available in XinCheJian at your finger tips, but some soldering is expected if you are serious about using them.
This is one of the simplest module you could find for USB to UART, the original product page is here: (With chinese documentation)
The Pin out of the module is
This module will work under both 5V or 3V.