There is no definitive link between EMF and cancer. And frankly even if you don't have a single device with WiFi in your home, you still are bombarded with EMF of varying frequencies and amplitudes on a daily basis. Nearby cell phone towers. TV and radio broadcast stations, satellite signals, and many, many more sources. Not to mention your neighbors with their WiFi networks. If you use a cell phone, that's far more powerful EMF right next to your brain. But no one has gotten brain cancer from using a cell phone.
The cancer.gov web site has this to say about cell phone use and potential cancer concerns. It completely relates to WiFi, as it uses similar frequencies and power levels:
Cell phones emit radiation in the radiofrequency region of the electromagnetic spectrum. Second-, third-, and fourth-generation cell phones (2G, 3G, 4G) emit radiofrequency in the frequency range of 0.7–2.7 GHz. Fifth-generation (5G) cell phones are anticipated to use the frequency spectrum up to 80 GHz.
These frequencies all fall in the nonionizing range of the spectrum, which is low frequency and low energy. The energy is too low to damage DNA.