Telnet to your router and type the command:
> portmaptime ?
Usage:
PortmapTimeSetting [-<command> <parameter> | … ]
-t <sec> : set TCP protocol session timeout.
-u <sec> : set UDP protocol session timeout.
-i <sec> : set IGMP protocol session timeout.
-w <sec> : set TCP WWW protocol session timeout.
-s <sec> : set TCP SYN protocol session timeout.
-f : flush all portmaps (useful for diagnostics)
-l <List> : List your all setting
> portmaptime -l
—— Current setting ——
TCP Timeout : 86400 sec.
UDP Timeout : 180 sec.
IGMP Timeout : 10 sec.
TCP WWW Timeout: 60 sec.
TCP SYN Timeout: 60 sec.
Just double or triple the default UDP timeout value.
> portmaptime -u 360 and press ENTER
—— Current setting ——
TCP Timeout : 86400 sec.
UDP Timeout : 360 sec.
IGMP Timeout : 10 sec.
TCP WWW Timeout: 60 sec.
TCP SYN Timeout: 60 sec.