Question about Brother HLL3220CW LASER PRINTER - SWI

The printer can print "manual" duplex.
1) Printer prints all reverse sides first
2) Then the printed pages must be put back into the paper drawer by hand in reverse.
3) Then the printer prints the front pages.

Works relatively well. It is not necessary to turn each page individually. With 20 pages, the stack of 20 pages is simply placed back in the paper tray upside down.

However, this is not fully automatic duplex printing.

By the way, here is the official instruction manual from Brother.
I always do it as described in the first section "Manual duplex printing via the standard feeder (paper cassette)"
https://support.brother.com/g...