Sketch of variability scenario in IRAS 20216+4104. The inner part of the disk of massive protostar wobbles due to the interaction of a nearby low-mass companion with the orbital period of ~14 yr and alternatively eclipses the two hemispheres of the central protostar. The eclipse modulates the scattered light in the outflow lobes (blue and red arrows) and the dust temperature, causing the maser (green ellipse) intensity variations. The shades of grey encode the relative irradiance of the outer disk. The orientation of the major axis of the disk and outflow lobes and the maser location is from the observations (see the caption of Fig. 8), but the sizes of the model components are not shown to scale.