Ok, just got done with the Comcast technician at my home and and unfortunately Comcast is not able to provide my router with a boot config to support higher upl

Ok, just got done with the Comcast technician at my home and and unfortunately Comcast is not able to provide my router with a boot config to support higher upload :( I just get the default we is still giving me 5Mbs upload and somewhat ironically I now get 300Mbs download (previously 70Mbs). Has anyone put a custom boot config file on a home cable modem? Any resources you would recommend? Is this a fools errand?