LB2120 Setup Info for Fail Over situations?

[AaronLTek]

Searched all over, cant find proper setup instructions to use this as a fail over for a down cable internet connection?

Does anyone have experience with this?  I've already wasted $70 in data becasue it failed over, and not back - did not recconect.

Also, I've had it not fail over but handed my ASUS router an IP Address... not sure why.

I need to know things like...

1. Should I change the DHCP in the LB2120 to had out IPs that are on the same subnet I already use on my LAN (192.168.2.x)?

2. Is it normal for the LB2120 to be handing the LAN router (my ASUS) an IP address - bascially taking the place of what the cable modem usually does.

... etc

Thank you for the help!

[AaronLTek]

UPDATE...

Attached screenshots showing configs of ASUS & LB2120

I think I'm close... I put the LB2120 in Bridge mode with ASUS Wifi Router (also the firewall) in the LB2120's DMZ (LB2120 has default IP 192.168.5.1 :: ASUS has static IP of 192.168.5.2)

Problem is, the LB2120 is blocking incomiming communications and/or ports. With just my ASUS router running (LB2120 not connected) everything works as expected. 

It looks like the LB2120 is not passing external (WAN) communications to the ASUS.  When I use my mobile apps that request data/comms from the Internet -- connection is initiated from teh Internet, it never reaches the apps inside my network.  When the internal apps use a cloud proxy (Hikvision, Samsung, etc) where the internal apps initiate the comms (from inside my network)... the mobile apps work fine.

Thus apps that go directly to IP:port (or DDNS:port) do not ever connect.  I verified that DDNS is working properly, correct IP.

Anyone have any ideas?

thx for the help