Boost Your Wireless Using An Old Router

I notice that my DD-WRT Frimware for D-Link 615 C1 does not have the repeater option in the drop list. Instead, it has other two options called WDS (Wireless Distribution System). For what I have seen, it looks like a repeater option too, but it may work different. But i haven’t found the way to make it work as well.

1. I would like to ask if you could make a tutorial of WDS Station and WDS AP.
2. Also, i would like to know if i can use either a repeater or WDS to boost an encrypted signal.