Thanks all for thinking with me!
My 4GB CF is partitioned in 3 partitions. One a couple 100 MBs And 2 others both just below 2GB. I just realised I only tried copying to one of the two bigger partitions. I don't get the error if I copy between the partitions or from a floppy or other CF in the PCMCIA slot to the IDE CF.
I don't have any Samba daemon on the Amiga as I don't share Amiga folders, I only connect to shares on my NAS, using the out of the box EasyNet software.
BTW, how/where can I determine what the errorcode (and others) mean?