Is this correct that they DON'T have to be the same speed? The agent said they DO have to be the same speed. As well there is an old post from 2009 that speaks to the same.
My only experience with this is on the business end - a friend has 1 modem that is 10x2 and is the public wifi for his business and another modem that is 15x5 for his point-of-sale system and office PCs.