Sep 25, 2014
Sorry to hear about the trouble! Grouped playback does require substantially more bandwidth than individual playback of both speakers would. If possible we would reccommend testing the product designated as the group "master" with either "great" signal strength or an ethernet connection to the router, just to see if the same problem occurs in this configuration.
Here are some other considerations to look into with a problem like this:
We're glad to hear this feature is working correctly for you. For the future we would be very curious to know which setting on the time-capsule needed adjustment to solve this unique symptom with playback?
Thanks for sharing, and happy holidays!