The better upload requires using their modem/router, or one of the specific users owned ones that are approved by them to work with the mid-split tech. While my old modem could technically do it, it wasn't "approved" for the speed. I was limited on upload to 35 but could usually hit 45 from over provisioning. I had to buy a new modem but now I get 1400/200. They just flipped the switch on being able to use consumer owned hardware at all with the mid-splits this fall.
Maybe I'll have to call in and complain. Seems to be the only time the get things working. I originally got the 1Gig plan because it had the highest available upload they had because I used to sometimes stream. I have an SB8200 so there shouldn't be anything preventing higher uploads.
Wonder if a competitor moved into your area. Only reason Comcast ever seems to make improvements is when a competitor with something better rolls into town.