I realize what follows isn't exactly what you're looking for, since you
already have the antenna, but any port in a storm, perhaps? Also since you
mentioned having a big antenna, this product has an antenna upgrade available
to take you from the included 5dBi antenna to a 9dBi one, kicking the price
from $45 to $59.
So at the risk of recommending the obvious and/or already attempted, how
about this?
https://www.thinkpenguin.com/gnu-linux/penguin-wireless-n-usb-adapter-w-external-antenna-gnu-linux-tpe-n150usbl
In terms of compatibility, it's specifically listed as being compatible with
Trisquel 6, 7, and 8; says it requires neither proprietary drivers NOR
firmware (acknowledging nadebula.1984's post); and has the Free Software
Foundation "Respects Your Freedom" Certification.
More links:
https://ryf.fsf.org/categories/wireless-adapters
https://www.thinkpenguin.com/catalog/wireless-networking-gnulinux
