I have always got good download and upload. Today modem lost everything but power. When came back it has slowed down to download 7.3Mbps and 1.8Mbps. I'm at 33% so shouldn't be dapped. Don't know what is going on.
Sometimes these things are temporary. You might check the weather at your gateway location. And sometimes things are degraded for a half-day or so for maintenance/repair issues. If you see a daily pattern to the slow down then it is most likely congestion and there is not much that can be done in the near future.
Like JEP said, there could be many reasons for this. If you're back to your normal speeds now, you should be OK, however, if the slow speeds are still happening you can send an email to firstname.lastname@example.org with your account information and we can take a closer look at it for you