I've been experiencing strange download behavior in a torrent manager on archlinux. Whenever I try to download a torrent my speed starts dropping and getting back to the same level again and again.
For example: my max speed is 250 kb/sec in any torrent manager, as soon as I start a download the speed gradually drops from 250kb/sec to 100 kb/sec and then to 0 kb/sec in ~30 seconds, when it reaches 0kb/sec it starts increasing up to 250kb/sec back again. The cycle continues for the period of the torrent download.
I can overcome this issue by setting "no encryption" in torrent download settings. When "no encryption" option is used, the speed stabilizes and does not jump. This behaviour is being noticed in any torrent manager I tried. I didn't have this issue on debian with the same configuration.
ADSL modem configured in bridge mode.
What can cause this issue? Any ideas?