Dear, please some one support this device.
Not very likely, even less considering the age of this device and the fact that xDSL modem and wireless wouldn't ever be supportable anyways.
See https://openwrt.org/toh/netgear/dgnd3700v2 for downloads + installation instructions
In this 2.4ghz wireless interface is not supported, can anyone help in this?
Without 2.4 GHz, no use of this router, as maximum connection are connected to it.