It’s not about one being stronger than another for everyone: it’s about what is already active at your own building so you can figure out which channel will have the least interference. See the following FAQs for more discussion ( these are clickable links)
Z wave and wifi don’t interfere with each other, so you don’t have to worry about that.
But WiFi can drown out nearby zigbee, particularly boosted Wi-Fi.
At my house, we have a Wi-Fi booster. If we plug it in on the north wall in one room, all the smartthings – controlled zigbee devices to the west of it drop off-line. If we just move the Wi-Fi booster to the east wall, all the zigbee devices work fine.
So the first step is to make sure that your SmartThings hub is at least 3 m away from your Wi-Fi router or any access point.
But sometimes the problem is bigger than that, and your Wi-Fi router is broadcasting on a channel which is just drowning out your zigbee devices.
You do have the option to change your Wi-Fi router, typically between channels 1, 6, and 11, so what’s the best Wi-F…