Here is the screenshot of my artboard in Illustrator:
As you can see, the dash lines is faded even when I don't use gradient. Do you know why is that?
Try wider strokes. Try also to avoid nearly horizontal and nearly vertical lines. If they are very narrow, they should be exactly horizontal or vertical to avoid severe anti-alias smoothing, which makes one pixel or less wide lines partially transparent.
Illustrator seems to be able to show narrow strokes as wider than they actually are to retain solid colors on the screen. But your target system hasn't that ability.