The Automatic Document Feeder takes more than one sheet at a time when scanning. I found the same defect with 3 4101fdws I purchased and replaced over the course of a few weeks.
Print quality was terrible, splotches everywhere. Had to se for heavy paper to avoid the splotches, which added to print time. Didn't have 2 weeks and had to send back as document feeder malfunctioned and wouldn't reset.
Followed all the (confusing) instructions and am unable to get the printer to find, and sign in to the network, despite having the correct password, the printer being 3' from the computer and the router within 10'.
I purchased this printer/scanner for my home office. I love the size as it fits perfectly where i intended it to be. It runs smoothly with minimal noise when it prints. The quality of the copies is HP perfect.