Apple has just made OS X 10.10.4 available through the App Store. It is a large download – over 1 GB – and contains many bug and security fixes.
It looks as if it drops the troublesome
discoveryd service discussed here, and claims more reliable discovery and connections. Once my update is completed I will clarify this.
iOS 8.4, ready for new Apple Music, is also available now, and thankfully is far smaller.