Vodafone, a major carrier in the UK, is telling customers that own the iPhone 4S smartphone to not upgrade their devices to iOS 6.1. The updated operating system, released by Apple last week, added more functions to the Siri personal assistant and improved iTunes Match. But according to Vodafone, it also introduced a number of connectivity issues, preventing users from sending or receiving text messages and connecting to the internet. The carrier says that the problems are intermittent and do not affect all users, but it is advising everyone to wait until Apple has addressed the problems before upgrading their devices.

We have reached out to Apple for comment on the matter and will update this post if we hear back.