Before installing Roon ARC, I listened to music outside the house using USB Audio Player PRO. To do this, my smartphone has a 1 terabyte memory card with a copy of my entire music collection. I'm pleasantly surprised by the sound quality of the Roon ARC at home. But, as I understand it, files on the smartphone are not accessible for Roon ARC? Now the only hope is for high-quality mobile Internet outside the home?
Describe your network setup
Internet 1 gigabit per second. Router ASUS RT-AC1300G PLUS. The gaming computer with running the ROON core is connected directly to the router via wire. There are no problems with this.
I too have a phone where i have well over 500 gb of downloaded music. I use UAPP and other applications that access the same music folder. ARC does not do this.
This means that you will have to download a copy of the music for use in ARC only. Be careful though, because it is easy to have to redownload everything again. After the third time I had to redownload my set of test music into ARC was the last straw. I will never use ARC for downloaded music on my phone and will stay with UAPP.
I use ARC only with streaming services or music from my home server.