Another update - I’ve set the network to a static IP address and disabled the firewall as described here:
This seems to have made musicbox/the network connection much more stable. I’ve been using a combination of the MopidyMobile app for general control as I prefer the interface to going directly to the musicbox IP address (mainly the behaviour of hitting the back button on the mobile whilst browsing for files).
As an aside… as a complete beginner in setting up an RPi I was happy I stumbled across Midnight Commander for editing the rc.local file - a really useful tool for editing files.
Thanks for your help, I’ll look out for RC5!
Andy