A fair number of WiFi chips need non-free software which Trisquel being free software only doesn't provide or support. So this is most lilely your problem. For now use a wired connection and then either get a free software compatible USB WiFi from this list:
https://www.fsf.org/resources/hw/endorsement/respects-your-freedom or Thinkpenguin do free software friendly PCIe cards which fit some laptops, however, speak to them first as not all laptops will let you change the internel (PCIe) WiFi card because of manufacturer anti-features. Leny
