UK carrier Vodafone has sent a text message to iPhone 4S owners advising them not to upgrade to iOS 6.1 if they haven't already.
According to the carrier, the update causes 3G performance issues: "If you've not already downloaded iOS 6.1 for your iPhone 4S, please hold off for the next version while Apple fixes 3G performance issues."
Vodafone confirmed the news to Pocket-lint: "We've just told iPhone 4S customers not to download iOS 6.1 while Apple works on a fix."
The confirmation comes after we had been contacted by a number of 4S owners saying they were experiencing issues. Anecdotally, Pocket-lint's own iPhone 4S on Vodafone has been experiencing abnormalities since the 6.1 update. We've struggled to send text messages and battery life has been affected.
Apple first released iOS 6.1 to the masses on 28 January. It features LTE for more countries worldwide, the ability to purchase movie tickets via Siri, and download individual songs via iTunes Match.
It's not clear when Apple may release iOS 6.1.1, though it has entered testing with developers.