[Night_Thastus]

The trouble is that there are a lot of situations that could be causing that.

Is the coax line leading to your house in good condition? Is your ISP performing some kind of maintenance on their local infrastructure? How new is your modem and what does it support? What about your router? Ethernet cables or wifi? What about the computer that's interfacing with it, is that the bottleneck? Is all the relevant firmware up to date? What is connected to your network and what is it doing?

I have high end networking equipment that's all kept up-to-date and I generally get a bit higher than what is advertised.

If you have poor quality or old modem and router, they're never going to be able to handle 500 mbps down.