@schtumb
Hey
The MAX Rate is what the line can physically achieve, however there is virtually no chance this will be stable at that max rate, you also have the slight overhead of any error checks your ISP have in place. The Current Rate you are seeing is what the Modem and DLM Profile will allow / negotiate to provide the "best overall experience". No ISP is going to let you push this to the max as they risk loss of connection / instability or high errors, therefore they always play it safe and choose stability over speed.
That is why in most European countries that profile is set to 40/50 or 80, im guessing your profile is 80. Your line could be capable of more but the profile wont let you, take a bit of overhead and some error checking.. 76 seems good to me
IMHO what you are seeing seems within expectations, there is physically nothing you can do your side to increase this as the profile simply wont let you connect faster. It may connect at 78 or even 79 but its going to be the rare occasion that conditions are perfect and will likely be temporary
I have a customer has FTTC into his office, the router line reads as 82 max possible (similar to you), however his ISP profile is set for 50 and he gets ~48 connection. Its all restricted by the profile ultimnately