No need to ping yahoo.com; that was just to test DNS in case the first two pings succeeded.
You totally lose communication with your ISP, so that's a problem with the ISP, the modem, or the cables between ISP and modem.
You have only one (high quality, two-way) splitter between the ISP's coax cable and the modem, right? Disconnect and reconnect each connection from the modem back as far as you can go to try to cure any corrosion or looseness problem. Assuming that there is a cable junction with a ground wire outside pay special attention to those.
You totally lose communication with your ISP, so that's a problem with the ISP, the modem, or the cables between ISP and modem.
You have only one (high quality, two-way) splitter between the ISP's coax cable and the modem, right? Disconnect and reconnect each connection from the modem back as far as you can go to try to cure any corrosion or looseness problem. Assuming that there is a cable junction with a ground wire outside pay special attention to those.