Strange behaviour with AirPort Extreme

My setup at home includes an iMac, MacBook, Apple TV and an AirPort Extreme. My airport has its own password, and the network drive attached has its own seperate password (which are different). Infuse refuses to connect to the network drive, with the suggested ‘guest’ username and device password.

Instead it connects with my MacBook username and MacBook password, which mind you, are different to the network drive… It also connected with my iMac password and username, which are again different, AND were on a different network in a completely different house at the time.

Sorry but wat.
Anyone else seen this before? My good friend with identical setup experiences the exact same issue.