re: Wifi bandwidth question

Wifi is very finicky, you can never count on it being consistent. Interference, multiple devices connected, different speed standards (G, N, AC), obstructions, etc... it's a miracle it works at all. And close proximity isn't always the best.

But if you are getting consistent speeds and they are just slower than expected, I would guess your router is in mixed mode (this is typical), and for whatever reason most of your devices are falling back to wireless G rather than N or whatever. Maybe see if there is a firmware update for your router.