D-Link Exo AX DIR-X5460 User Manual page 76

Section 3 - Configuration
Advanced Settings... - Application Level Gateway (ALG) Configuration
PPTP
Allows multiple machines on the LAN to connect to their
corporate network using the PPTP protocol.
IPSec (VPN) Allows multiple VPN clients to connect to their corporate
network using IPSec. Some VPN clients support traversal of
IPSec through NAT. This Application Level Gateway (ALG)
may interfere with the operation of such VPN clients. If you
are having trouble connecting with your corporate network,
try turning this ALG off. Please check with the system
administrator of your corporate network whether your VPN
client supports NAT traversal.
RTSP Allows applications that uses Real Time Streaming Protocol
(RTSP) to receive streaming media from the Internet.
SIP Allows devices and applications using VoIP (Voice over IP)
to communicate across NAT. Some VoIP applications and
devices have the ability to discover NAT devices and work
around them. This ALG may interfere with the operation of
such devices. If you are having trouble making VoIP calls, try
turning this ALG off.
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