The most common high speed internet problems whether its DSL or cable connections are not being able to log on and poor signal.
If the Cable modem often reboots, you should check to see if your signal indicator is strong. If the signal seems good, electronic signal from mobile phones and other devices nearby may be interfering with the signal.
Stop and look behind the cable or DSL modem to see if the connections have worked themselves loose or have come off completely. Be sure the connections have not be damaged in any way.
The modem is connected to an Ethernet card which will receive and send signals to the computer. Look at the rear of the card and see if the green indicator is on. If not, there is a problem with the card installation or the card may be faulty.
If the Ethernet card in the computer become loose, your high speed Internet reception will be interrupted. Place a finger on the Ethernet card and try to move it. If you can, open the system unit case and tighten the card.
If the Ethernet card has become loose, it may be a good idea to remove it and inspect the yellow contacts to be certain they are not dirty or damaged. Power will not transfer to the card should this be the case.
Other causes may be the main wiring to the modem may be faulty. The vacuum cleaner or the power tools your son is using in the garage may be causing the problem as well. And we cannot omit the idea that the cable or DSL modem themselves may be faulty.
While you're learning about your computer, understand the modem at every level and do so now while it is still in good operating order. Print or write down modem and all troubleshooting tips.
Put these troubleshooting tips in a binder or at least in a safe place so you can refer to them should your PC fail to boot. Knowing about your computer takes time and effect but you be glad you took the time should your system goes on the blink.