I have HP server on my network which is used as media server to stream video to multiple locations in the house. Setup consist of Dlink DIR655 router, and couple of dlink switches. All hardware supports gigabit speeds. Wiring is CAT-6. Weird problem is that when I transfer data from PC to server speed drops from 80MB/s to 15MB/s in the middle of transfer - most of the time it happens when I trasfer large files 1-5 GB. What could be the reason? It's so frustrating.