Draytek VIGOR2925 SERIES User Manual page 205

Network Mode
APN Name
MTU
WAN Connection
Detection
After finishing all the settings here, please click OK to activate them.
Force Vigor router to connect Internet with the mode
specified here. If you choose 4G/3G/2G as network mode,
the router will choose a suitable one according to the actual
wireless signal automatically.
APN means Access Point Name which is provided and
required by some ISPs. Type the name and click Apply.
The maximum length of the name you can set is 47
characters.
It means Max Transmit Unit for packet.
Path MTU Discovery – It is used to detect the maximum
MTU size of a packet not to be segmented in specific
transmit path.
Click Choose IP to open the following dialog.

Path MTU to – Type the IP address as the specific
transmit path.

MTU reduce size by– It determines the decreasing size
of MTU value. For example, the number specified in
this field is "8". The maximum MTU size is "1500".
After clicking the "Detect" button, the system will
calculate and get the suitable MTU value such as 1500,
1492, 1484 and etc., automatically.

Detect – Click it to detect a suitable MTU value

Accept – After clicking it, the detected value will be
displayed in the field of MTU.
Such function allows you to verify whether network
connection is alive or not through ARP Detect or Ping
Detect.
Mode – Choose ARP Detect or Ping Detect for the system
to execute for WAN detection.
Primary Ping IP – If you choose Ping Detect as detection
mode, you have to type IP address in this field for pinging.
TTL (Time to Live) – Set TTL value of PING operation.
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Vigor2925 Series User's Guide