I suspect it's a more general clarification on Internal Router, as it clearly works for some wireless bonuses, but not others, and which isn't clear, so is a lot of GM calls.
The explanation for most wireless bonuses (sometimes in fluff, sometimes in crunch, sometimes by players) was that the device had to rely on distributed processing power or information sources on the Matrix. Some never fitted that well, and would be good candidates for Internal Router.
I hope none of my players want one, don't really want to have to make calls on everything a player considers fitting.