Any help with an error "connection refused"

[chaban]

I suspect you are blocked because your IP is listed on the QNAP blacklist

Can't connect to Musicbrainz.org website and Picard doesn't check music on home network

That’s a long story, but basically QNAP devices are querying our webservice abusively, currently 70% of the incoming traffic is from such devices, but the bad thing is that most users aren’t aware of it, and it doesn’t serve any purpose (users don’t complain at all when we block those queries at http level). But we are now blocking at IP level, to spare more bandwidth, so only legit and regular users of MusicBrainz having a QNAP device actually complain, and we whitelist them. The whole story …

I’d contact MetaBrainz directly and give them more details:
https://metabrainz.org/contact