Packet Loss

I am experiencing severe packet loss. I've run numerous speed tests (including the one here for Xfinity) and my speed is great. I've restarted my devices numerous times as well as replace my cable modem to take advantage of the higher speed available. But I am still having packet loss across the network...specifically with 2 comcast addresses. Using PingPlotter I am having upwards of a 60% loss on one of these (the other is around 18%). This started a few weeks ago and I'm getting a little frustrated with it. The topic lists my home network, but it has nothing to do with my home network.