Simple answer, please: What does "connection closed by peer" mean?

[Spherix]

On occasion I'll get the "connection closed by peer" status on a bunch of the trackers in my µTorrent client. For me, it's a temporary thing, and mainly happens if I've got a whole lot of torrents active at once (not necessarily transferring pieces, just in the "seeding" state), and I've overloaded my cable modem's connection table or angered my ISP's traffic shaper. I've never had the persistent kind of problem most people seem to have when they see this error message. I just restart µTorrent and the problem goes away.

Why did I write all that? Because I don't want people responding trying to tell me how to fix the problem. I've seen far more of those threads than I care to have read while trying to research this error message. I just want to know what it's supposed to mean, and where it comes from. Is it a µTorrent-specific message, or is it from some other part of the network stack?

Just reading the error message, it sounds like another peer in the swarm has disconnected me from the tracker. I know that can't be right, but that's what it sounds like. Peer has a meaning in relation to BitTorrent, but I can only conclude that it's not the meaning being used here. Thus, I think it's a poor error message. Puzzling over its possible meaning, my best guess is that it means the connection attempt was canceled somewhere between my computer and the tracker, instead of at the last hop, which is what would be expected if the tracker was offline.

So, could anyone clarify this?

[DreadWingKnight]

The "peer" in this case is the tracker itself, the message is something relayed from the TCP stack in the operating system.

Running fewer torrents at once may reduce the frequency of the message (or outright eliminate it) if your modem is indeed overloading.

Sometimes it could simply be that the tracker itself is overloaded beyond the point that it can fully establish connections, and nothing you can do can solve it.

[Spherix]

Sorry to bring this back up after a month, but could someone clarify the difference between "Connection closed by peer" and "timeout"? Just guessing, I would assume that the former indicates that the "peer" has responded in some way, but hasn't fully established a connection, whereas the latter indicates that there has been no response whatsoever.

Also, I still don't understand why this message is passed on to the user in the way it is. I imagine it's been around for a while, and the only person who'd really know (ludde) is no longer in charge of the project... But I personally find it confusing, and believe that it confuses a lot of other users as well, thus leading to the incredible amount of messages about it on the internet (seriously). At the very least, it seems like a common enough error message to be included on the FAQ, but I'd suggest that the message be changed to something that makes more sense to the average user.

Edit: And here I finally find this page (the title of which seems incompatible with the bbcode url tag): "http://wiki.theory.org/Problem_connecting_to_tracker_%3D_(10054,_'Connection_reset_by_peer')"

So now I'm even more confused.