I've personally talked to CypriotMerks about this situation. He told me that people that are experiencing this need to refresh their DNS. I haven't tried it yet, but it's worth a shot.
How many network connections do you have? My friend has 2. If he connects to the wrong one, he can't connect to servers.
They are not running a VPN. @juliet2374 would you happen to know which Minecraft version you are running? If you don't know how to find this open up the Minecraft launcher, once opened it should say in the bottom right (Just right of the big Play button) under your sons username. "Minecraft 1.x" (x being any number)
Try updating to the most recent version, Minecraft 1.9.2 I believe it is. To do this you need to go back in the launcher, then click on edit profile (bottom left) there will be text saying version and next to that a dropdown box, click on the dropdown box and you will be given a list. Go to the very top of that dropdown box and there should be a version saying 1.9.2, 1.9.1 or 1.9. Select either one and click save profile. Then click play and hope that makes a difference c: I'm writing this off memory so hopefully those steps are correct :p
