For over a year, I have experienced periodic massive drops in download speeds. It can happen any time of day.
The solution is to turn the modem off and back on - a pain, of course. This returns me to normal speeds instantly [30mbps for me] every time.
Once the download speed is diminished, it stays that way until I restart the modem. It does not self recover.
Last year this happened at least every week for months. Then it didn't happen for months and now it has begun again.
What is going on?
Is that your final solution, or are you maybe looking for better technical advise after many months of not calling Spectrum for help?