14 DAY TRIAL // iOS 9 was released on September 16, but according to Cisco's AnyConnect team, the operating system still has some bugs in it, breaking VPN connections for some network configurations.
Cisco's AnyConnect Secure Mobility is a VPN client provided by the company, regularly used by enterprises to allow their employees to safely work and access the company's internal network from remote locations.
Back on September 8, the Cisco AnyConnect team issued an alert, letting users know of an iOS 9 bug reported with the operating system's first 9 beta release, which was not fixed for the final 9 version, and is currently unaddressed in the company's 9.1 beta release.
According to the Cisco team, the problem lies in that, "when doing Split Tunneling, the Tunnel All DNS option no longer functions as expected."
This means that, depending on how the VPN network was constructed, employees using iOS 9 devices to access the company's Intranet may experience issues connecting to it.
Downgrading to iOS 8.4.1 is the only solution, for now
As ZDNet has found out, currently, the only way to get around this problem is to revert back to iOS 8.4.1 until the issue is resolved. This can be achieved in two different ways: the easy way, or the painful way.
The easy way depends on whether you created a backup of your system using iTunes, before upgrading to iOS 9. If you have, just restore the backup and you'll be just fine.
The painful way of downgrading to iOS 8.4.1 is by reinstalling the operating system from scratch, but this also resets the device to factory settings, so beware of any data and settings that may be lost.
The VPN bug does not affect Apple's other operating system, OS X, in any older or more recent versions.