The 503 error indicates that the tracker site has temporarily gone down. Itâs a âservice unavailableâ error from the web server, and most of the time indicates maintenance or some similar condition. Just stay with it and see if it fixes itself.
When the trackerâs down, you canât obtain an updated peer list, and neither can anyone else. Your client doesnât have anybody it can initiate a connection with, and nobody else can initiate a connection with you, because neither of you knows the other exists. (Thatâs what the tracker scrape does, it provides you and them with a list including each otherâs IP addrress and listen port.)
All youâre left with is those you can find via DHT. But time should cure the situation, as theyâre hopefully working on the web server.