When “opening the door” on seder night, does one open only the door of his apartment, or all doors leading to the public?
Is there any difference when it comes to opening the door between Shabbos versus a regular yom tov?
This custom is to symbolize that this night is “leil shimurim” – the night of protection, and so we open our doors to show we are not fearful of the forces outside. It would seem sufficient to open the door to one’s apartment to fulfill this custom. This will also avoid unnecessary delay in proceeding with the seder. There is no difference between Shabbos and Yom Tov [there used to be a custom to go to the door with candles, this would only be possible on Yom Tov].