Hey Norm
No, I wasn't trying to use Home Sharing. None of my devices (MackBook Pro, MacMini, iPad, iPhone) were able to connect or were only able to connect intermittently to iTunes Match, the iTunes Store or iCloud for around 1 hour that night. No other internet services were affected so it was something specific to Apple. Logging in and out made no difference, some devices were able to log back in, some weren't but then the devices that could log in went into loops trying and failing to synchronise libraries and playlists and iCloud Photos started a full upload of everything on my MacBook. Luckily it hasn't duplicated anything so at least that part of it works ok. In the end I went to bed and left it to it, it was fine in the morning and no re-occurence.
Thanks for pitching in 🙂
Tim.