low upload speed

I have the 2 gig plan and my upload speeds are not whats advertised. I am only getting 35 mbps. My moden is netgear cm3000 which is on the approved list and capable of handling the speeds. By looking through this forum it seems like no one is getting the advertised upload speed. Is this why xfinity speedtest only gives you download speed and doesnt test upload speed so your customers doesnt see they are not getting what they pay for?