If I'm transferring a file between PC and laptop via router, why am I limited to....

[Chapbass]

Unplug the uplink and see what happens. Or do a traceroute from one computer to another and see where the packet is going. One thing you can also try is directly connect the two to each other. I don't want to be "that guy" but are we talking about the same two computers? any chance that the laptop hard drive just sucks that badly?