Honestly... it took me a bit to find where I typed it also; something that important should probably stand out better
I'm not exactly sure which config file you're refering to. If I missed a link to something explaining this I'd appreciate that very much. The diagnostics page of the modem isn't very informative beyond what I pasted above but from poking about the web I believe the modem goes up to 32Mbps (though I could be dreadfully mistaken ).
Honestly... it took me a bit to find where I typed it also; something that important should probably stand out better 
).