I'm using fw 11.831.05.01.420 for around 20 days on umg 1831 without any problems, and let me clarify ghpk's concern, the other thread he is referring to and the guys with bad firmware upgrades have issues because they upgraded firmware for different modem, not something which people in right mind should do ..The link you referred to is perfect for upgradation, please go ahead with peace of mind and let it finish properly. Its not always better speed you get with latest firmware, but more stability and even lesser heat, better reception also.