So the problem looks to be that either packets were not delivered to SoundBridge or ACK replies were not getting back to mt-daapd.
I’ll not dispute that at all, these tests were deliberately done to collect data in marginal wireless network conditions so that the problems would happen.
I will be reorganising the domestic network setup at the weekend and should, hopefully, stop getting any such problems myself. But hopefully the data gathering will help others who see the same symptoms.
Anyway over to you experts to ponder over that data 😉