About “Always-on” function, normally you need to combine "Healthy Check" function together, then
"Always-on" can work more perfectly because there is an ADSL modem between router & ISP equipment. In
physical layer, if ADSL line fails but ADSL modem is still alive, and router can not detect the line status unless
ISP sends a disconnected packet to router. So if ADSL line is in abnormal up-down, sometimes router can not
get disconnect packet from ISP. Maybe in ISP side, it treats line as disconnected status, but router seems like
to be still in "connecting" status.
If you enable "Healthy Check" in each line, then router can automatically send packet out through WAN to
detect whether line is active or not. (1 packet per 30 sec) This function will be helpful to judge the line status,
and provide correct information to router for the Link Status.
It's better to enable at least 2 options in "Healthy Check", in order to avoid misjudgments when only 1
option is selected and the option server fails to respond the request.
3.3.3 WAN Type – Static IP
When user applied the leased line from ISP, the service provider will offer user the real IP, Subnet Mask,
Gateway and DNS. You need to indicate the static IP manually. (Figure 3-9)
Figure 3-9 Static IP
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