You don't need to do any router configuration to access Realplayer streams. "Trying to access Realplayer" - you mean starting the program, or accessing streaming files? Does the router actually drop the connection, do the relevant lights go out, what exactly do you see on screen when the connection drops. The PC dropping the connection and the router dropping the connection are two different problems.
By the way, if RP is only used to access streaming internet media I would recommend its removal and replacement with click here