Did you resolve your issue? I also have a problem with fan noise and swapped for a new modem and this second one has the exact same problem. I have plenty of open space around it and don’t want to go back and have to try a third modem!
Same for me. It's way louder than any desktop pc I've had and really annoying... Is there any point in getting it exchanged or will the new one be just as bad? Probably... Maybe have to buy a 3rd party modem for $150 :(