Apple Watch 3 LTE connectivity issues get a fix with watchOS 4 update
http://www.techradar.com/news/new-watchos-4-patch-solves-apple-watch-3-lte-connectivity-issues
Today, though, Apple released an update to watchOS 4, called watchOS 4.0.1, to owners of the smartwatch, and it apparently solves the issue.Few features make the Apple Watch 3 so appealing as the available built-in LTE and Wi-Fi connectivity, but following its launch two weeks ago, reports of spotty connectivity quickly rolled in and stoked concerns.
Apparently the Apple Watch 3 LTE was still constantly seeking out unauthenticated Wi-Fi networks, causing it to ignore the sweet plan you paid for when it finally latched on to the public signal at Starbucks or elsewhere.