Apple has been forced to admit that the biggest selling point of its latest smartwatch doesn’t actually work too well. And it goes sale tomorrow (22 September).

A version of the Apple Watch Series 3 comes with cellular LTE connectivity. However, the Watch appears to be connecting to unknown wi-fi networks as opposed to a cellular network – presenting substantial connectivity issues.

The problem, which was first identified in reviews of the smartwatch by the likes of The Verge and the Wall Street Journal, has led Apple to say: “We have discovered that when Apple Watch Series 3 joins unauthenticated Wi-Fi networks without connectivity, it may at times prevent the watch from using cellular. We are investigating a fix for a future software release.”

Despite Apple’s promise of a software update, there is no word out on when we can expect this to arrive or how the update will fix the problem.

The Apple Watch Series 3 was unveiled last week, alongside the iPhone X, iPhone 8, iPhone 8 Plus, and Apple TV 4K. Pre-orders for the Watch began on 15 September, and it officially goes on sale tomorrow for $399 with cellular connectivity and $329 without cellular.