If your AP is up high on the pole, the signal may be going overtop the cabin instead of inside. A gain omni antenna works by concentrating signal into a horizontal plane. Antenna gain is more significant at the higher frequency.
you could always add another Unifi AP with just power and set it to mesh inside the cabin. not ideal but could help. i like using the U6 Mesh as mesh points.
you could always add another Unifi AP with just power and set it to mesh inside the cabin. not ideal but could help. i like using the U6 Mesh as mesh points.