Nxt / Ardor not downloading blockchain, it just stuck and hangs on startup at "known peers" I have a fresh install of nxt / ardor and it just hangs on "Known Peers:". I waited a few hours and nothing happens. How can one debug this issue?
Make sure your firewall allows outgoing connections on port 7874 or 6874 on testnet. 

You can also try to invoke the getPeers API from the http://localhost:7876/test page with "active" set to "true". You should see a list of IPs your connected to, if you don't see anything, double check your 7874 port.