Weirdly, some are and some aren't. 11.1 seemed to completely fix my BT issues, while it didn't fix others earlier in the thread, and for still others BT problems started with 11.1. There's obviously ...

My previous machine (same location and orientation wrt my BT speaker) was a late 2009 mini, and I never had this problem. I'm tempted to get it out of storage and try some more tests. Anyway it's old ...