I think after 5 years I finally figured out the end all solution for this problem. I think most of the problems of this machine are symptoms of the same problem. The first things to go are the wifi and treble indicators. The fan starts getting really loud. Then the machine starts overheating after a few more months and shuts down periodically. I think that all of the problems are due to overheating.
What I did to solve it is that I took an air compressor with a little air blower attachment at the end. I blew about 20 puffs of compressed air into the vent underneath the processor (and graphics processor?) on the bottom rear left- where the biggest air vents are. This probably loosened up the dust collecting around the processor(s) and lets it get the cooling airflow it needs. The machine is also running quieter and cooler. The wifi hasn't died at all since I tried it. I hope this helps.