I'm getting the same thing, but no one on their end is responding to anyone. They aren't giving any kind of explanation. I'm under the impression, especially after their technician told me themselves, that they are causing these nightly problems themselves. The guy claimed that they are 'scanning' our connections from their end for hours starting roughly 6-8PM and it can last a long time. Considering they're refusing to explain, I'm leaning in the direction of believing it. I honestly wish I could get something else, but I have no other option than simply no internet.. And I'm about to go down that path.
Please start here if you wish;