Just today, after several weeks time lapse, I received this clarifying response from Audirvana:
Hello,
We are aware of an issue with Tidal in the Audirvāna 3.5 version and we are actively trying to find what is going on with Tidal directly. We are in contact of their project coordinator and they will come back to us as soon as possible on this subject as this issue seems to happen to some of our users but not all of our users.
This is why we suspected in the first place that it would may be an issue related to public IP that have been banned or something like this on Tidal side. For the moment this supposition has not been confirmed by them but we are waiting for Tidal to give you an explanation about what is going on.
We know this has been around for a long time but we are dedicated to tackle this with Tidal and we will reach you back as soon as they have something to share on the state of this issue.