ZeroBrane Studio, an OpenSource Lua IDE https://studio.zerobrane.com/, has awesome remote debugging capabilities https://studio.zerobrane.com/doc-remote-debugging
If you have the code you want to debug, you just need to add the following line
require('mobdebug').start("10.5.5.140")and it will connect to your computer (being 10.5.5.140 your computer) and will allow you to go step
by step, dump variables, etc.
For this to work you need to install two packages on the router: luasocket and lua-mobdebug
root@LiMe-abcd00:/# opkg update
root@LiMe-abcd00:/# opkg install luasocket lua-mobdebug