https://bugs.launchpad.net/ubuntu/+source/apt-cacher-ng/+bug/1034392
The original bug was reported in 2012 but recent comments are from 2018 and 2019: Steve Dodd (anarchetic) <https://launchpad.net/~anarchetic> wrote on 2018-07-07: #17 <https://bugs.launchpad.net/ubuntu/+source/apt-cacher-ng/+bug/1034392/comments/17> I am seeing this on a box running 14.04 (acng 0.7.26-1ubuntu0.1) - nothing leapt out when I strace'd, I will try again and save to file. I am also not sure that strace-ing didn't "unstick" the acng process, which would be very odd .. I will also try backporting a more recent acng and see if problem still exists, Andres Jalinton (andresj551) <https://launchpad.net/~andresj551> wrote on 2019-01-24: #18 <https://bugs.launchpad.net/ubuntu/+source/apt-cacher-ng/+bug/1034392/comments/18> - logfile2 <https://bugs.launchpad.net/ubuntu/+source/apt-cacher-ng/+bug/1034392/+attachment/5232299/+files/logfile2> Edit <https://bugs.launchpad.net/ubuntu/+source/apt-cacher-ng/+bug/1034392/+attachment/5232299> (234.2 KiB, text/plain) I'm running an Ubuntu 14.04 and Ubuntu 16.04.5 serving the DEB cache with apt-cacher-ng. The download of files to the older (and tested in other distros debian based) is very slow (10 to 50 kbps) Attached are the strace files.