Hello. I upgraded my subscription plan from 100mbps to 350mpbs but i have a slight problem/misunderstanding? My download is the same as it was when i had 100mbps. Steam still downloads games at 11mb/s max speed. My ethernet card is 10/100/1000 if that helps.
Doesn't matter how fast your connection is if the server has limited capacity.
Right now is a horrible time to speed test. ISP's and services like Steam are getting hammered right now. Since so many people are at home due to coronavirus isolation. You'll have to wait until this is all over and people go back to their normal routine. To get any reliable measure.
The Steam download speed is in MB/s not Mb/s. 11MB/s is 88Mb/s. Which is pretty good.
Also you say your card is gigabit. Is the cable CAT 5E or better. Everything must be Gigabit. Your NIC, Router, Switch, cables, keystone jacks, RJ45 connectors, &c. If one link in the chain is 100mbps. Everything will be 100mbps. Which sounds like the case as 88Mb/s is about the practical limit of a 100Mb/s connection.