I would not recommend any high traffic hosting from home. It maybe much cheaper for you to host your game server from I web hosting company. You must consider an increase upload bandwidth, high latency on a non symmetrical isp network, electric bill to run that server, and I decent spec out server that can handle the load when hosting servers. If you are not going to have a lot of traffic latency will be your biggest problem and 400k will not be enough.
I personally have a 20mb down and 2mb upload internet connection with a lot of servers and it is a hassle trying to manage bandwidth between, www, ftp, bit torrents, email, voip, etc. Not to mention the cost of electricity and cooling, and the $99 a month internet connection.