If you have OOL, and you slow down at night, it is probably just the node being a bit overcrowded.
Try testing your speeds at different times of the day.
You can use the Automatic Test here --->
http://www.testmy.net/tools/test/scheduled_test.php to set up tests automatically.
Remember, cable is a
shared network. If too many OOL customers get online on your node, you will slow down, and there is not much you can do. Just keep notes on your speeds, and what time you get those speeds..
I went through hell and back with OOL trying to fix my speeds....I found the fix...
FIOS! 