On Linux, you can change the UDP buffer size (e.g. to 26214400) by (as root):
sysctl -w net.core.rmem_max=26214400
The default buffer size on Linux is
You can also make it permanent by adding this line to /etc/sysctl.conf:
Reference: Improving UDP Performance by Configuring OS UDP Buffer Limits. It also provides methods for changing UDP buffer sizes on Solaris, FreeBSD, Darwin and AIX.