Never heard of 6.4Ghz….but 90% of smokers on the market use 2.4Ghz. The reason is that the lower the frequency the further the travel of the signal. Also most companies are combining the 5G and the 2.4G “as a Smart connection”…..so most smokers have issues with connecting to these “smart” routers.
You can either work with the internet company to split apart the frequencies, or buy a repeater 2.4Ghz cheap router just for your IOT devices like smokers.
Not saying that the PitBoss 1600 is “the smoker” to buy….but most of them use the 2.4Ghz frequency….AND….that should be the last reason to pick a smoker is for the WiFi signal and not the Controller/Smoker capabilities and how well it makes Ribs and Pork Butt.