It’s easy, particularly when traveling, to end up connecting to a Wi-Fi network that doesn’t provide Internet access, requires credentials you don’t have, or lacks access to the network’s printer. Unfortunately, once your iPhone, iPad, or Mac has connected to such a network, it may reconnect to it later, causing consternation when things don’t work. The solution? Whenever you realize a Wi-Fi network is worthless, forget it. (The network, that is.)
On Mac, open System Preferences > Network > Wi-Fi > Advanced > Wi-Fi, select the network in the list (you don’t have to be connected to it), click the – button, and click Remove. This will work whether the offending network is nearby since you’ll see a list of all networks your computer remembers.
On iPhone or iPad, when the network is nearby, go to Settings > Wi-Fi, tap the i button to the right of the current network, and tap Forget This Network on the next screen.
If you use iCloud Keychain, you will only have to do this on one device, since all of your Apple devices share WiFi information.

(Featured image based on images by iStock.com/fizkes and Elena Pimukova)