Usually not. There may be an undocumented switch somewhere in the firmware that a good driver could tweak? Depending on the exact hardware. But end-user termination boxes, whether delivered by the ISP or purchased by the end-user, are built for as cheap as possible and ship with whatever under-the-hood software configuration the manufacturer thought was a good idea. Margins are just too narrow to pay good engineers to do the testing and digging to fix performance issues. (Used to work at a company that sold high-margin enterprise edge equipment, and even there we were hard-strapped to get the buggy drivers and firmware working in even-slightly-non-standard configurations. Though 802.11 was most of the problem there.)

And in the case of telco equipment, that's an tradition-minded and misguided conscious policy decision.