The amount of pages is totally irrelevant, computers deal with data size, not pages.
A single page of text in pdf format without OCR can be as little as a few Kb, or well into the MB's in size, what matters is the content of the pages, a bunch of black text on a white background is small, the identical sized page (Letter/A4) containing a full color picture at 600DPI will be massive in size. Both are still one page.
Run a wireshark trace of the scans(small and big) and read that to find out which side is failing and why, if your printer is up to date in firmware it will have the trace feature built in
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