Can anyone explain this?

[wes8398]

Ok, I've done lots of reading around and I understand that my ISP (Bell Sympatico) basically sucks for torrents. I thought I would share something very interesting that I observed tonight though; and I'm wondering if anyone can explain it.

I was having the same problems as most others with torrent files being stuck at around 30kB/s download speed so I started googling and searching this forum for possible fixes. I found a thread that suggested the usual things like disabling DHT, forcing encryption, and disallowing incoming legacy connections. It also suggested changing the port Utorrent uses to 1723.

So, I followed the instructions, and opened port 1723 in my router. To my surprise, my 3 running torrents climbed to download speeds exceeding 500kB/s .. the fastest I've seen with this Bell connection.

HERE'S WHERE IT GETS INTERESTING...

The next time I open and use Utorrent I notice that it's back to the same old 30kB/s download speeds. So I randomly just changed the port in Utorrent's settings...WITHOUT even opening that port in my router's settings and BAM ... downloads are all running around 300kB/s as we speak.

THIS CAUGHT MY ATTENTION, SO...

I closed and then reopened Utorrent ... same file that was just DLing at 300kB/s is now back to 30kB/s. Went into settings and randomly chose another port .... BAM ... speeds back up again. Again, this is WITHOUT even opening these ports through my router's settings.

CONCLUSION...

I have no idea! One thought is that maybe Bell sees us opining these ports in our router settings and obviously they know what we're going to use it for, so they just automatically throttle that port. When we tell Utorrent to use a port that's NOT the one we opened in our router settings, Bell's throttling isn't there ... why, I don't know?

Thoughts anyone??

[Ultima]

They probably use a bandwidth throttler that is made of fail. Random guess, but maybe they're sniffing packets communicated to trackers, read the port sent, and throttle only that port. When you change the port, µTorrent reports the new port to the tracker -- the throttler sees this and then stops throttling on the old port. Since connections may still remain on the old port (they shouldn't have been terminated after the port change), this results in those old connections speeding up again.

After changing the port to a new one and letting the speeds rise, try changing the port back to the old one and see what happens.

[wes8398]

It seems that whenever I change Utorrent settings to the port that's actually been opened in my router's settings, speeds plummet. When I change Utorrent's settings to basically any other port, speeds sky rocket. Strange, eh?

[Ultima]

Not particularly. It melds well with my above-posted hypothesis.