Buggy routers may cause network problems

Buggy routers may cause network problems
If you experience network problems during the installation, this may be caused by a router somewhere between you and the Debian mirror that doesn't correctly handle window scaling. See #401435 and this kerneltrap article for details.
You can work around this issue by disabling TCP window scaling. Activate a shell and enter the following command:
echo 0 > /proc/sys/net/ipv4/tcp_window_scaling
For the installed system you should probably not completely disable TCP window scaling. The following command will set ranges for reading and writing that should work with almost any router:
echo 4096 65536 65536 >/proc/sys/net/ipv4/tcp_rmem
echo 4096 65536 65536 >/proc/sys/net/ipv4/tcp_wmem