There are a number of ways in which the poem shows disconnection, but specifically to the hostel (which would include the place and its occupants) you could talk about the simile in: 'For over two years we lived like birds of passage'. A bird of passage has no home, it is itinerant, not unlike the experience of the persona and his family. They too live as if ready to move on at any moment. They don't even bother to keep track of the 'comings and goings' of the other migrants who remain nameless and faceless, such is the level of disconnection.
The simile comparing the barrier to a reprimanding finger in: 'as it rose and fell like a finger pointed in reprimand or shame' also suggests this disconnection as the hostel takes on the persona of an alienating authority figure, one which prevents the family from establishing a connection to the new world in which they find themselves.
