Do toddlers ever sleep

[Elliesmommy]

Have an almost 4 year old and a 2 year old
( also a 6mth old but hes going to bed ok)
Same routine every night. Bath , chats , toy each to play with and into bed. They come wandering downstairs . Up we go. I threaten to close door if they come out again. Queue banging on doors. I'm losing my mind. What am I doing wrong? Bedtime is becoming a 3 hour ordeal of them testing mine and my husbands patience. What can I do ?

Are they in the same room waking each other up? Are they scared and wanting comfort or just bored and fancy playing? What happens if someone sits on with them until the drift off?