What DNS servers are you using for host resolutions?
You don't show many errors in your downstream, so I am guessing the issue is with the upstream side. I have a feeling it might be noise intrusion.
This is something SDL L3Tech
should be able to help you with.
Don't know if they are working tomorrow or not, but you should go ahead and send him a pm, with your modems mac address and your public IP, and also reference this topic.
Good luck, keep us posted.