Have you tried 2880dpi? Are you following their print settings? What media type setting are you selecting in the driver? Are you using sheet or roll media? Does this happen on any other rag paper- or only the Canson Velin? Are these bands vertical (as opposed to horizontal/print head direction)? Are all nozzles printing well on your nozzle check? Is your printer aligned to the Velin paper thickness? If not, you may want to realign your printer with this paper.
If you are only having this issue with the Canson paper, and are using their recommended settings, then I suggest contacting Canson for support with this strange pattern you're getting in your prints.
Please keep me posted, I'm curious what you discover.
Best regards~ Dana