Well there's nothing wrong with your downld speed there. 50 + KB/s is close to the maximum of a 512 kbps connection. This varies depending on overhead losses such as distance from ISP provider, losses due to hardware such as your connection device.

Your Asus device doesn't show the model number on that image. But I think there is a + sign there which may give more information about this. What you need to try to do is find UPnP (Universal Plug & Play) option to turn on. Look in the Advanced Set up option of your device & see if there's UPnP mentioned anywhere. If not, then manual port forwarding might be in order. It would help to have a model number. But I've seen at least one Asus model does have UPnP support. It's found under Advanced options.