I had a couple of issues similar to this and in one case, I had to unplug my Sonos Bridge from the switch. Once doing so, everything worked fine. More recently, I had a problem with my internet and although I could surf the web (slow), Audirvana would load, but not play. Specturm found a coax cable outside my house with a crack in it and water was getting in.
Also, although this didn’t fix either issue, make sure your Ultrarendu software is up to date (2.7). According to Sonore, even if the UR is at 2.7, download new software anyway. Here are tthe instructions they gave me:
Please update the software once a month on the unit. Go to MySonicorbiter for the latest software. Yes it will still say V2.7 regardless but nevermind that the software needs to be updated once a month. It’s probably now at V2.799
Once the software is updated then soft reboot the unit.
Then after the soft reboot do a hard reboot.
Finally once its up again and before you do anything else, reboot the DAC. Now go to http://www.sonicorbiter.com under system and Hit save under the application you are using. If you are using DLNA then scroll down on the DLNA page and hit SAVE. You will find that going into this page and hitting SAVE will cure most of issues 99% of the time however once the issue becomes continuous you need to update software which typically are updated monthly.
I would get into the habit of updating your music software program, your DAC firmware and the Ultra Rendu firmware. All three devices are computers which need constant maintenance.
Hope this helps.