I was skeptical, but a fan does seem to help

I agree with the shelf and the restriction upon the location of the router you have little to no wiggle room. That is one of my bigger disappointments with the solution is that the location of the router is so critical for reception of signal. Heat can be an issue where optimal location results in conflict with the ambient temperature. I still have to wonder if there are some of the Nokia routers that are more prone to over temp issues due to hardware and a manufacturing anomaly. I have an early revision of the router from when I joined the BETA program. (3TG00739AAAA)  When there was a good bit of conversations about temperature and the router operations I did put my router out on the back porch on a 90 degree day and it kept on working and threw no alarms. Maybe I just am fortunate to have one that does not have heat issues.  If people with temperature issues contributed hardware revision information and other factors and a relationship could be identified that could make a difference. The fact that they did not incorporate a fan into the design where heat is generated seems to be a mistake to me. Passive cooling appears to be insufficient for some users. I am fortunate to have been able to get an improved traffic flow with a window on the NE wall where it is a cooler location. Not everyone has the luxury with the Nokia router to be able to avoid heat issues due to the imposed "location" of the router for optimal cellular signal strength and quality.