This question really seems more on topic using the libreCMC support channel,
not the Trisquel support channels. But what the hell...
The router usually has an admin interface to upload firmware images. Go poke
around inside the admin interface looking for it.
Found it? Great! Continue on..
https://librecmc.org/librecmc/downloads/snapshots/v1.3.4/ar71xx/luci/ has v1
and v2 and v3 images. No, that's not the version of libreCMC - It's the
hardware version of your router. Go grab you router. Turn it around. Look at
it upside down, right side up and sideways for anything that might say if
it's TL-WR1043ND version 1 or TL-WR1043ND version 2 or TL-WR1043ND version 3.
If it's TL-WR1043ND version 4 you are out of luck for freedom. Sorry!
Anyway, once you know the hardware version you will see there is more than
librecmc firmware image for each version. That is because the "factory" one
is intended to be flashed when you're running the original factory firmware
while sysupgrade is intended to be used if you're already using librecmc.
Ta Da!