If you need more help with your printer, you can find helpful links from Brother here.
Support & Downloads
Search for your model and access support information:
https://support.brother.com/g/b/productsearch.aspx?c=au&lang=en
Online User Guides
A4 Mono Printers and MFDs
HL-L6400DW:
User guide - https://support.brother.com/g/s/id/htmldoc/printer/cv_hll5000d/asoce/manual/index.html
Other Resources - https://support.brother.com/g/b/manualtop.aspx?c=au&lang=en&prod=mfcl6900dw_us_eu_as
Downloads - https://support.brother.com/g/b/downloadtop.aspx?c=au&lang=en&prod=hll6400dw_us_eu_as
MFC-L6900DW
User Guide - https://support.brother.com/g/s/id/htmldoc/mfc/cv_dcpl5500dn/asoce/manual/index.html
Other Resources - https://support.brother.com/g/b/manualtop.aspx?c=au&lang=en&prod=mfcl6900dw_us_eu_as
Downloads - https://support.brother.com/g/b/downloadtop.aspx?c=au&lang=en&prod=mfcl6900dw_us_eu_as
A4 Colour MFD
MFC-L9570CDW
User guide - https://support.brother.com/g/s/id/htmldoc/mfc/cv_mfcl8900cdw/asoce/manual/index.html
Other resources - https://support.brother.com/g/b/manualtop.aspx?c=au&lang=en&prod=mfcl9570cdw_us_eu_as
Downloads - https://support.brother.com/g/b/downloadtop.aspx?c=au&lang=en&prod=mfcl9570cdw_us_eu_as