I tried pinging their box; timed out. Odd. The next step was to tracert; this had very spotty results. Attempts will time out anywhere from the third to tenth hops. I also see behavior similar to this ...

Diagnosing a slow internet involves a lot of guesswork. You might blame your router for slow evening internet, reconfigure your DNS settings to see if your ISP's DNS is causing the issue, or run the ...