Your modem doesn't allow ethernet bridge mode.
What you want is a modem that just sends "bridges" the real IP address PLDT provides to your wifi router.
It's your Wifi router that should handle authentication, DHCP, DynDNS and port forwarding.
I have 3 extra PLDT myDSL modems here sa office ko (that support bridge mode), I can give you one free of charge just to help you out. Basta here's what you need to know;
VPI/VCI: 0/100 for myDSL
You need to retrieve your circuit number because that's your myDSL username. It should be on your PLDT bill what your circuit number is for your DSL line. Your password then is {circuitnumber}@pldt.
There is a way to hack into the dareglobal... you have to telnet into it but if you don't know linux, medyo nosebleed and I can't instruct you how to do it easily.