no I guess, there are many difficulties to achieve your purpose, First, the long distance between the two sides, it may cause many latent network problem if there is no professional cabling;...

So your connection can be simplied like this (just considerate one adsl connnection): ISP -- adsl router--TL-R470T+--MAC mini OS X Server and you want to build up an IPsec VPN server in the 470T+ so...

And your settins is OK I guess.

The Load Balance router can intergate the two WAN's bandwidth logically but not physically. That is to say when WAN 1 connnection is busy, then the router will let the next connection to go through...

So， what is your last firmware version? Is it too old? It is recommened to update the firmware version by version or there may be risk of lose settings.

Hi Anach， what is the hardware version of your R600VPN? I have a R600VPN, its hardware version is 2, it support NAT lookback as I tested