Well, I can’t think of any obvious explanation for it. I think the problem is still that the ENC28J60 is not starting, but you said the LEDs on your laptop’s Ethernet jack lights up, and that’s strange. Do you mean your laptop or your router? How are you getting OS online?
Since I am also curious what’s causing the issue, you can submit a support ticket and send your DIY version back to us so we can take a look.