As a 56k player in the past I can suggest you set your rate in console to a number around 4300. If you roll 33k~36k V90 connect speed, that will be close to optimal. If you have a better connection you might up that a bit. If your connection is lower; you're pretty much doomed. 31.2k under V34 is not sufficient.
Assume you must be connected to the interwebs to the game to run, despite rumors I've heard, I've never gotten a Steam game to actually work offline.