Someone knocked at the door as foreigners do.

Can anyone explain this paragraph from Leo Tolstoy’s The Devil? (The translation is by Louise and Aylmer Maude.)

Someone knocked at the door as foreigners do. He knew this must be his uncle. “Come in,” he said.

The scene occurs in Eugène Irténev’s study. Eugène is the protagonist of The Devil, a conventional, basically decent guy who is consumed by guilt over his desire, never consummated, to cheat on his wife with an attractive peasant woman on his estate. Knocking on the door is an uncle, never given a name, who is staying in Eugène’s house. The uncle is a “flabby libertine and drunkard”, prone to bragging about his fictitious society friends.

Letting the uncle in, Eugène proceeds to confess his imaginary sins. The uncle fails to understand how his nephew can be so upset about a sin he hasn’t even got around to committing, and recommends that he and his wife take a nice long vacation to the Crimea. Eugène takes up his suggestion and manages for a few months to blot out his longing for the peasant woman; but on their homecoming, his desire returns, strong as ever, triggering a rushed and unsatisfactory denouement in which he takes violent measures to put an end to his guilt. (There are two versions of the ending, both equally unsatisfactory.)

But I’m concerned with the line about knocking at the door “as foreigners do”. Is Tolstoy saying that Russians don’t knock on doors before they enter rooms? Or is he saying that there is a particular kind of knock that is characteristic of foreigners? And why does Eugène recognize this uniquely un-Russian knock as belonging to the uncle, a character who is never described by Tolstoy as having lived abroad?

Is this the product of a clumsy translation, or is this just one of those things that only a Russian reader of Tolstoy’s era would know?

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Update, July 27, 2020: Added cover image and linked to Bibliography page.