In addition to Bluetooth, the Apple Watch also relies on Wi-Fi to communicate with its paired iPhone. In fact, the device canprovide a number of useful featuresover Wi-Fi wheniPhone isn’t in Bluetooth rangesuch as Messages, Siri and more.
It alsoautomatically connects to known Wi-Fi networksthat your iPhone, while connected to the Apple Watch over Bluetooth, has connected to before.

However, the Apple Watch won’t connect to a 5GHz Wi-Fi network, even if its paired iPhone has previously connected to it, as firstnotedby French blog iGen.fr.
I own a Time Capsule which supports dual-channel Wi-Fi networking.
I have set up two wireless networks on the device: one is 5GHz for devices that support fast wireless networking, and the other on the much slower 2.4GHz band for devices like the Apple Watch.
Then, I made sure to connect at least once to the 2.4GHz network on my iPhone when it was paired with my Apple Watch so that the watch would remember login credentials.
Read more:How to make Apple Watch connect with iPhone on a 5Ghz Wi-Fi network
In addition to 5GHz networks and those your iPhone’s never connected to, the Apple Watch also cannot connect to public networks requiring logins, subscriptions or profiles.
This is a software limitation because connecting to a password-protected public Wi-Fi without an iPhone at hand would require a software keyboard to input login credentials, which the Watch OS doesn’t support.
An Apple support documentdetailswhen the Apple Watch will fall back to Wi-Fi.
“If Bluetooth isn’t available, Apple Watch will attempt to use Wi-Fi. For example, if compatible Wi-Fi is available and your iPhone isn’t in Bluetooth range, Apple Watch uses Wi-Fi,” Apple explains.
When both Wi-Fi and Bluetooth are available, your Apple Watch will maintain connection with its paired iPhone over Bluetooth to conserve power.
“To enjoy every feature on your Apple Watch, you’ll need to enable Wi-Fi and Bluetooth on your paired iPhone,” reads the document.
To enable Wi-Fi and Bluetooth on youriPhone, just toggle the Wi-Fi and Bluetooth switches in the Control Center.