This was awkward. I found some info on the Web where someone had used a USB to Ethernet adapter and a Y-splitter cable to connect their Pluto to their LAN. So I got the exact same bits off eBay. Nope, no go. I resorted to asking on the very helpful Facebook group and tried all the advice, for example powering it via the separate USB power socket, but still no go. So, a process of elimination – the USB adapter worked fine on the Mac so no issues there, nor with the CAT5 cabling in use. But I did not have a separate mini-USB to USB socket cable, only the splitter cable. Back to eBay…
A cable arrived today and the Pluto appears on the LAN just fine. So it’s the Y-splitter cable that is at fault. Not tested it yet but it’s only a couple of quid so no biggie. Serves me right for not keeping things simple and using a splitter.
Anyway, one step closer to my QO100 project! All I need now is a decent way to get Ethernet out to the workshop. I do need a LAN out there anyway, not just the house wifi, so either a cable or a wireless bridge.