Thehas had problems connecting to LTE networks when around certain recognized public Wi-Fi spots, but a new software update could correct the issues.
The new Apple Watch WatchOS 4.0.1 firmware, available now, promises it "fixes issues that in rare cases were causing Apple Watch to join unauthenticated (captive) Wi-Fi networks, such as those found in public places like coffee shops and hotels, which direct the user to a web page before the network can be accessed."
The Verge and The Wall Street Journal first discovered the connection problems (I didn't encounter them as I wore the watch over the last few weeks). Apple confirmed to CNET that the Apple Watch avoids the connection problem by dropping off the public Wi-Fi spot and handing off to LTE, versus being able to connect to that Wi-Fi. But it looks like this update won't address : the Apple Watch Series 3 LTE won't send or receive SMS messages when the paired iPhone isn't on and connected to a network.
I haven't downloaded the firmware yet, but will update this post when I do.