said by lorennerol:If your ISP has you throttled to 5mbit, the bottleneck is on their gear, not at your router.
Your router can decide which traffic has priority to use the available 5 Mbits in your example. If you have the right router.
In almost all cases your ISP network is not saturated or overloaded, only the last mile link to your house is limited in speed. A good router manages this in both directions, given proper configuration.