Manually reconnecting (by closing dataviewer and relaunching it) seems to work better than the automatic reconnection.

[mikelovskij]

If during the call of the next() method of the nds iterator the exception "Requested data were not found" ir raised, dataviewer launches the self.reconnect() method, which deletes both the iterator and the connection objects, creates new ones and retries calling the next() method.
While this usually works, it seems that (for reasons don't understand at all), some time it happens that the automatic reconnection attempts keeps failing, while if instead by closing and relaunching dataviewer, the newly created iterator seem to work immediately.
I'm not 100% sure of this bug, since it could be that this happened just by chance and that the "manual" reconnection was just the one more attempt that was necessary for the nds2 connection to return working, but I'm starting thinking that it happened to me a bit too many times for it to be casual.

How to reproduce: use dataviewer, if after a while the nds2 connection fails and the automatic reconnection attempts keep failing, try to close and reopen dataviewer manually.

The issue is that the automatic reconnection attempt should not be different from a manual one, so I really can't understand why this happens. My only clue is that maybe something that helps in making the connection work happens when re-importing the nds modules.

Anyway just posting this to see if this happens to other people too in a reproducible way.