This should finger point you to the right way to change the initial temperature:
It required you to access SSH, but should be easy even with limited knowledge.
But tbh: 60C isn't critical. Just take a look at the temperature of your graphic card while doing some gaming, for example... they will easily hit 80C and more.
also the thread literally says that this solution works but not completely without other problems,
So why even trying if there is a chance that it breaks more than all ready is broken,
Fo the GPU yes 70 to 80C is a perfect work environment for it… but I am sorry this is not a forum for GPUs
The perfect temperature for routers is between 30C and less (just google it)
So 70C is just ridiculously high for a Fan to kick in, the Workaround is pretty good but not without other problems to account, in short we need to wait for a better solution or update,
If nothing else happens I‘m allready Designing a 3D Printed Mount for the Underside of the Router with 2 60mm noctua Fans