TP-Link router firmware modification?

Question

network hardware

Router TP-Link TL-WR 840N.
Are there ways to disassemble the stock firmware, make changes and assemble it back?
The idea is to sew up the connection parameters by default (connection type, login, password, MAC address, IP for remote connection). so that when resetting to factory settings, the necessary parameters are set automatically.
Perhaps there are some tools?
Can I read, watch, download examples somewhere?

Answer 1

I advise you to read this series of articles, much will become clearer and clearer.
https://pudeev.livejournal.com/26318.html