Speed difference between morning and evening is staggering

Azlen said:
I'm currently on the Ultimate Tier.  If I do a speed test early in the morning, I get speeds in the 150-180 Mbps range.  When I do the speed test in the evening, I get speeds in the 40-80 Mbps range and it's been getting worse.  The signal to noise ratios and power levels are the same each time.  It would seem that the bandwidth in my neighborhood is unable to support ultimate speeds during prime time.  Is there anything that can be done to fix that?

Your SNR may look good, but there is a reading we have called Forward Error Correction that your modem doesn't show you. Only Arizona that I know of has even introduced formal specifications for the FEC reading (other regions will follow, since it is more important the faster we get), and your modem is failing them:
 
It causes your modem to effectively throttle those channels down somewhat by adding redundancy/padding to compensate for the error rate. This throttling effect would be most visible on Ultimate.
In any case, the solution is the same with or without the FEC to back it up. We'd want to send a technician out as close to the time when you have a problem as possible. They'd find and correct any signal issues, and usually do a speed test with their meter at one or more locations. If they find the system still can't support the correct speed at the tap even after any detectable problems are fixed, then it would be escalated to next-level maintenance.