I don't use Debian so I dunno if you have the conf file or not.
nano /etc/sysctl.conf enter
If a file shows up then you may be in luck.
If not skip to the bottom of the post.
The first four line deal with window size and you need to enter numbers that are best for you (because these ones may be too high). Here is what I mean by this:
Computers communicate by sending packets of data back and forth. When they connect with each other to send these packets they use the TCP (Transmission Control Protocol).
Your computer could begin the connection with a small package size, then the other computer might respond with a larger one. In turn your computer will reduce (scale down) the size of the package (to a bit more that your original package size). The other computer again responds with a larger packet size. This cycle continues until your computer or the responding computer meets their maximum package size.
If you choose a windows packet size that is too big, you will notice slower broadband performance (524288 works for me). If you notice a slow down, then reduce your window size.
The largest size you can use is 65536, however these are the three settings that seem to work best:
Which are all multiples of 1024 (or 1K).
Now add the following to the end of the file:
net.core.rmem_default = 524288
net.core.rmem_max = 524288
net.core.wmem_default = 524288
net.core.wmem_max = 524288
net.ipv4.tcp_wmem = 4096 87380 524288
net.ipv4.tcp_rmem = 4096 87380 524288
net.ipv4.tcp_mem = 524288 524288 524288
net.ipv4.tcp_rfc1337 = 1
net.ipv4.ip_no_pmtu_disc = 0
net.ipv4.tcp_sack = 1
net.ipv4.tcp_fack = 1
net.ipv4.tcp_window_scaling = 1
net.ipv4.tcp_timestamps = 1
net.ipv4.tcp_ecn = 0
net.ipv4.route.flush = 1
After adding these line you do not need to reboot, instead just reset the file by issuing this command as root:
Check your repositories for powertweak.
If you hhave it, install it and make your tweaks from there.
I don't use it nor ever have,, just read about it.
If it isn't available, you may consider downloading and trying it from
Debian as well as most other distro's try to discourage installing from outside sources so use at your own risk.
Debian also has a wiki, you may find help there if someone can't help here.