I bought a Lumin U2 a year ago (also have a U2 mini). I have used it with no problems for a year. I run Roon on a SonicTransporter i7 with Tidal and ripped CD’s saved to SonicTransporter. Lumin feeds a Holo Audio May DAC. My router is a TP Link Archer BE9300 since November and before that an Alien Amplifi.
Lumin worked fine until last firmware update. About a week ago I woke up one morning to find it disconnected from network. On re-start it would play a song for a few seconds then disconnect again. I did two power cycles and a factory reset, and it finally started staying connected again.
This morning it was again disconnected. Several power cycles and factory resets, and I can’t get it to stay connected. After a restart, it will show up on network, but as soon as I start playing it (whether Tidal or music stored on hard drive), it disconnects and disappears from network per Roon, Tidal Connect, cx and Lumin app. Now after a power cycle I get the following message: “Rescue Mode Cannot find upgrade file Remove setting files” After looking around, I did a factory reset without USB from DAC plugged in, but this changed nothing. Also, after moving Lumin to desktop to do all this, I am starting to get static and popping on my system, although the cabling is close to power cables. I had started getting intermittent mild pops around the same time this all started, but had not started to chase that down yet.
The Lumin U2 Mini is working fine. I have disconnected everything except PC, SonicTransporter, and Lumin U2 from network for power cycles. Even after disconnect, the ethernet connection on back of Lumin has two green lights. The only other odd thing I have noticed is that I have to re-log in on Tidal after a factory reset and even after a simple restart, and sometimes I have to enter log in and password more than once. I have tried everything while logged off of Tidal, but it still wants to join. A few times after restart, it has cycled through songs without playing before disconnect.