Which WiFi?


iMac (Retina 4K, 21.5-inch, Late 2015)
MacOS 10.14.6

I have a WiFi setup that allows me to choose either the 2.4 or 5G channels on my TimeCapsule, and I also have two devices that use their own WiFi networks connecting to the router wirelessly: a Tesla backup battery and an Aquanta hot water system monitoring device. When I click the WiFi icon in MacOS I see a list of all four of these options with the selected network checked.

Recently, when waking from sleep my system seems to reselect which WiFi network to use, which I only discover because it has chosen either the Tesla or Aquanta network and some app is not connecting to the Internet. (I don’t know if this is related to the most recent MacOS 10.14 updates, because I don’t recall when it started happening.)

The Tesla and Aquanta devices need to connect to the Internet themselves to operate properly, but they do not set up WiFi for other devices to use, so I can’t just uncheck the “Automatically join this network” option in Network Preferences.

Does anyone here have experience with multiply WiFi networks running at the same location and know how to tell MacOS which one to use all the time?


You can select Network from System Preferences, then click on the Advanced… button. Under the WiFi tab, you can see all the networks your Mac knows about. You can either delete networks the Mac should never be connected to, or uncheck the Auto-Join checkbox.

This doesn’t makes no sense to me at all. Although most IoT devices do come with the ability to broadcast their own network initially, that is only so you are able to log into them and give them access to your WiFi network router. Once you have given them the routers SSID and password, they should automatically shut down their own broadcast having connected to your router and the Internet. In any case, as long as those two devices are working properly with Internet access, David’s recommendation should prevent your issue going forward.

I will also add, that in most cases you should not establish separate 2.4GHz and 5GHz SSID’s, but rather let your devices decide on their own which will give them the fastest service. A few users have sworn to me that that doesn’t always work for them, but it’s what most network experts recommend and I found works best for my setup.