Hmm, first we need to know exactly which model it is. But I'm going to assume it's the Internet Box 3. Because it has an SFP+ connection. However, this is now for the WAN side and not for your home network, which makes the DAC obsolete. In addition, it won't help anyway, as the router doesn't have 2x 10Gbit connections and you won't get 10Gbit anywhere through the box. If you really want fast data transfer within your network, you need to hang other/better hardware in front of the router. For example, hang a Dream Machine in front of it and then 10Gbit switches or you probably don't need this on all devices, then a 2.5Gbit switch is probably not a bad choice either.