Lumin U1 Mini - how to set up Network *without* Ethernet cables?

To Lumin owners. I just got the Lumin U1 Mini. Had Limetree (Lindemann) Bridge before.

Need to connect the Lumin streamer to my wifi network. There won’t be any ethernet cable as my router/modem (from ISP) are in a different room than where the music and DAC need to be.

I’ve downloaded the Lumin app but the dum  app seems useless. It presumes the Lumin is already on the network. Which is a bit of chicken and egg as there’s no way on the device itself to connect to the network -- how would I enter the wifi password etc?

Any ideas how I get it on to my wifi and set up the password etc? The online manual is horribly un-informative. Does Lumin presume everyone will use Ethernet cables to connect to modem/router?

I am little surprised this is what "audiophiles" rave about. The basic setup is not even thought-through. And manual refers only to "iPad", most users will use their iPhone. Welcome any pointers.