Hello jimr. Please download and install PingPlotter pro (free trial) and run traces to your current DNS servers and to a specific (ping-able) site/server that you can reproduce the problem with. Please do not trace to Speedtest.net since it is just a portal page to the actual speedtest servers.
You can post the image here and PM me your cable modem's MAC address (found on the modem itself) and your public IP (»whatismyip.com
) so I can start looking into it.