Stupid question but you say his crate is on the landing, do you have another crate or are you feeding him on the landing in the crate?
I have a crate in the kitchen and what I did was feed in there, give a Kong in the day in there but shut the door on her - I stayed in the kitchen and prepped tea / cooked tea etc that got her used to going in the crate in the day.
Then I worked up to leaving the room at first just to get the wash basket that was in the hall to walk back in and empty the machine (this helped me do the washing in peace
and built up the trust that I would come back)
I have 4 crates
one in kitchen, one in bedroom, one in the study (I work from home) and last one in the car
Ash very rarely goes in the kitchen crate now unless I need to leave her in the house and pop out without her. In the day she goes in the study crate and curls up
Night time she used to sleep in the crate in the kitchen but since she hit 6 1/2 months she sleeps in the crate in the bedroom
You have to decide on what you want and be consistent - when Ash was 11 weeks I would put her in kitchen crate to nap in the day - I would close the crate door, yes she whined but soon settled as she was tired, it’s like having a baby, you know they are tired (but cockers don’t like to give in they may miss out on something
)
You will get there - wishing you all the best