First question: is your Upsampler AES 1+2 connected to the DAC 3+4 as recommended at p.18 of the Upsampler manual for network audio? Not sure it would matter for the problem you describe. Anyway, good luck with that. I had a very odd occurrence with my brand new Upsampler yesterday. After playing flawlessly for about 48 hours, I did some system simplification. I removed the BHK preamp after determining I preferred the SQ without the preamp (and the convenience). This meant turning everything off of course and removing power. When I fired everything back up, my Upsampler began losing its Network lock every 10-30 seconds. And of course the DAC would immediately show no input. No music could be played. The unit would briefly appear in the Roon Audio device fab, but then disappear. And the Upsampler did not appear at all in Mosaic. This was frustrating. I did more than one power recycle and did a Config reset to factory defaults. No change. I reset the streaming interface in the settings tab of the web server. Except for occasionally having to wait for the server page to load, or sometimes not being able to load it at all, the server page showed the correct info for the Upsampler (including its static IP of 192.168.1.125——but that should have been the clue to me, because I believe a reset to factory defaults restores the Upsampler’s DHCP-assigned addressing). In the Network Info screen on the Upsampler, it showed its IP address—whenever it would briefly lock on—as 192.168.1.125. Again, this should have been my “aha!”. Finally, I checked the switch to which the Upsampler was connected. It showed a live connection, but I rebooted that. No change. I thought about swapping Ethernet cables. But first, I unplugged the Ethernet cable from the Upsampler, and then plugged it back in to make sure it was properly seated. And then boom, the Upsampler locked back on to Network but with an IP address of 192.168.1.103. For some reason, it couldn’t let go of its past life as 192.168.1.125 until physically removed from the network by unplugging cable. And she has been playing sweetly ever since.
BTW, in all this time since the Upsampler’s introduction, could dCS have perhaps installed an Ethernet port with LED indicators like every other device on the planet? Just sayin’.