We have an issue like this: We print PDFs from a Linux box to a printer attached to a Windows machine.

Problem is when we print from the Windows the printout comes perfectly with the font bold and clear, but when printing from the Linux box the font is very FAINT and we can see dots in the fonts.

We tried changing the PDF to a text file (i.e. we created text file with the report) with the -o cpi=5 option and still it does not come out properly. Now the font gets bigger, but we can see dots in the font and it is not bold.

Any help would be greatly appreciated.

Is the printer made by Brother?

First check the printing settings you use when you send the work, especially the quality (low quality prints fast, but has smaller dpi than high quality). I'd also check whether the settings guide the printer to use black or color for printing; I've met some cases where color was used to print "black", which was more like grey or blue than true black.

Edit: if it's not the settings, then it's very probably the driver you're using. Check that the driver you are using is meant for that exact printer model you use, and that it has been tested to work (e.g., is not commented as "works somehow" or equivalent), if you downloaded it from somewhere.

Epson LQ-300+II