This year I've flown between ARN and LHR on EI-SIA x2, -SIF x 5, and once each on -SIG, -SII, -SIJ, -SIH and OY-KAO. Wifi service has been about 50:50. Doubt it's deliberate, it just seems to be a fairly difficult service for on board staff and ground crew to fix when it's not working. On at least one flight the cabin crew announced that the plane was so new it hadn't had the wifi equipment installed.