A+ and UPnP not working anymore in 3.5.1

After updating to 3.5.1 on my main system Audirvana is now completely unusable:

  • UPnP is not working anymore (DAC is recognized but playback not working)
  • A+ is not finding the computer anymore and can not connect

I already had the same issue with the version prior to 3.4.919.
I now had to move back to 1.3.10 - but now with limited A+ functionality.

How can I rollback to the stable release 3.5 and suppress automatic updates?