Draytek Vigor2762 series User Manual page 148

Available settings are explained as follows:
Item
Enable ALG
Listen Port
TCP
UDP
138
Description
Check to enable such function.
Type a port number for SIP or RTSP protocol.
Check the box to make correspond protocol message packet
from TCP transmit and receive via NAT.
Check the box to make correspond protocol message packet
from UDP transmit and receive via NAT.
Vigor2762 Series User's Guide