Wi-Fi troubles with a B&W Zeppelin Air and AirPort Extreme/AirPort Time Capsule?

Recently, my B&W Zeppelin Air speakers have started to show a weird problem: I managed to stream music via AirPlay to them, but they would only play the music for a few seconds, then stop for a seemingly random amount of time, then play the music for a second or so again, then stop again, and so on. A lengthy stuttering, so to say.

Turns out, the reason for these troubles was that I set the AirPort Time Capsule’s main SSID wireless security to “WPA2 Personal” and the guest SSID’s wireless security to “WPA/WPA2 Personal”. Now I’ve set them both to “WPA/WPA2 Personal” and the Zeppelin Air works great again! Streaming also works fine if both “networks” are set to “WPA2 Personal” (which is a somewhat safer setting than WPA/WPA2 mixed mode, some old Wi-Fi cards might not work anymore, however).

I can’t quite explain this, based on the observed symptoms (one would expect things to either work or not work, but not half-way). It seems the AirPort Extreme/Time Capsule has troubles using different wireless security protocols for the main network and the guest network. This might also partly explain the generally shaky Wi-Fi connectivity I’ve experienced since upgrading my Macs to Yosemite – the random Wi-Fi connectivity drops even kept occurring in 10.10.2. I’ll keep an eye on it.