Calling search with cards_page crashes after page 10

I am trying to get all disabled(archived) cards in a board, so I am trying to use the search endpoint in the API. The query I am using is below(with idBoard, key and Token removed), and I’m running it in a loop. As soon as cards_page gets to 10, the server answers with Status 503.{key}&token={token}&idBoards={idBoard}&query=is:archived&modelTypes=cards&cards_limit=1000&card_fields=closed,dateLastActivity,idLabels,name&cards_page=0

Am I doing something wrong, or is this a bug?

What is the error message that comes with the 503?

What API key are you using?

Any reason to not query the cards nested resource for the board directly? Something like{idBoard}/cards?filter=closed&limit=1000