Win 10 but the server is running on a PI. I've never had an issue before and it buffers and checks all data so I cannot see that being the issue. I've printed quite few large items and never had this. i cannot see it being a data or buffer issue given it happens on the exact same side every time. The defect is nearly identical layer to layer also. Yes it's solid. It's one of 4 quadrants of a dead pedal I made for my RV. I use 20% infill and use supports usually. This one I did not but no issues w/ any of the holes. I didn't care as they were getting drilled/tapped anyway.Dave