And mine often fail but I try anyway.
For starters, ETHERNET can be on average, on a good day, while all is good and well (I'm trying to avoid writing about Full Duplex, 10, 100, 1000 MegaBit) has many advantages over WiFi.
We have this on most Ethernet networks:
1. Full Duplex.
2. Switched Hub.
3. 100 or more MegaBit speed.
Since WiFi has to send data to the router, then the router has to relay that again over WiFi to the NAS you can suffer about a 4 to 1 speed drop. You can improve this by placing either the NAS or the computer on the Ethernet ports.
Nothing's busted here. But I find no one will attempt to explain it.
Bob
In CNET reviews of external HD and NAS read/write speeds the charts say in Mbps. The speeds for nas(time capsule, wd my book live) are an order of magnitude greater than the wired speeds of external hd. What am I missing?

Chowhound
Comic Vine
GameFAQs
GameSpot
Giant Bomb
TechRepublic