We can handle uploads as large as 500MB and remotely-hosted files larger than that, but the larger a file is, the more time it will take to download, so that increases the probability that some technical glitch could possibly interfere with the download process for any of a wide range of possible reasons unrelated to anything at our end.
It sounds like most downloads of your 160MB file are working fine and only about 10% of buyers are having issues, so you can use your Seller Admin > "Re-activate expired download link" (if they expired their permitted attempts) and "Send free download link" (if they can't even get a reactivated link to work) functions to help those buyers out.
You might also consider adjusting your product's download expiration settings to allow more Attempts (we recommend at least 5 attempts, no fewer than 3 at bare minimum, up to a maximum of 9) and a reasonable hour limit that would expire the link even if they haven't exhausted all permitted attempts (expiration is determined by "whichever happens first").
