constant server connection failures with on demand functions

I have encountered that problem with my hopper 3 from time to time, but after a few tries it usually resolves itself and starts downloading. There was one time when it took almost 10 minutes to resolve. On the occasions when I get the same failure messages you , once again it just usually resolves itself after a few more tries like within a minute so I haven't had this problem last much longer than that, but I can understand your frustration.