Comment 23 for bug 59331

I had the same problem with a server serving as a proxy using hardy (8.04.2) and on my laptop using Jaunty (9.04), the same issue on both sides...

I solved it by using this in /etc/sysctl.conf:

net.ipv4.tcp_wmem = 4096 16384 512000
net.ipv4.tcp_rmem = 4096 87380 512000

and afterwards, to make changes efective without restarting:

sudo sysctl -p