When enabling my Windows Phone for Office 365 I consistently received the below error when using Wifi, but not when using a mobile data connection. The same error appeared whenever my Office 365 email account attempted to synchronize, again, only when using WiFi.

data connection error Windows Phone

A quick online search showed I was not the only person with the issue. One user captured the issue on video, and even highlighted that the same Office 365 email account on an alternative phone was unaffected.

I verified this same observation. My Office 365 email would synchronize on my iPad over WiFi, and at the identical moment, the same email account on Windows Phone would result in an error.

The fix to the issue is hinted in the comments of the above video, disable IPv6.

For those not familiar IPv6 is the latest version of the protocol to route traffic across the Internet. The existing protocol, IPv4, doesn’t have enough addresses for all the devices that will want to communicate over the Internet. Right now, there are some methods to address the IPv4 restriction, but in the long term IPv6 provides a permanent solution. For comparison purposes, IPv4 has about 4.3 billion addresses, IPv6 has 340 billion billion billion billion. There are other reasons for the latest IPv6 protocol that you can read if interested.

IPv6 functionality is not supported by all Internet Service Providers, and not all broadband routers have IPv6.

So how do you disable IPv6?

IPv6, if you have it, will be an option on your broadband router. This is only relevant if you have the simplest of IT setups, where your broadband router allocates addresses to your devices for Internet access. If you have an IT setup that was installed and is maintained by others, then ask them to read this post :).

Below is a screenshot on a Sky Broadband router. While Interfaces obviously vary, there will be something similar on most broadband routers for home or small business.

ipv6 on broadband router

To disable IPv6, untick the box “Disable IPv6″. Right now your devices will continue to work using IPv4 addresses – this will already be enabled, and there is no action to take with IPv4 settings when disabling IPv6 settings.

This immediately resolved my issue.

How do you log in to your router?

This is a site for small business owners without onsite IT support, as such let me cover how you actually log in to your router for those that don’t know.

You will need to type the IP address of the router administration page into a web browser. In the earlier screenshot you will see I used This address varies according across providers. Per earlier comments, assuming you have the simplest of IT setups, the easiest way to find the IP address for your broadband router is to Google, e.g. “Sky broadband router admin address”. A username and password will be required. To find the defaults credentials, consult Google again, e.g. “Sky broadband routers default admin username”.  If the default settings have been changed it is best to contact your provider for assistance.

So why exactly does IPv6 cause a problem?

To be honest, I do not know exactly why IPv6 causes an issue. But, the independent validations, including my own, give me confidence that it is the fix:

One online comment proposes why IPv6 causes the issue, “on my WLAN, I had been running IPv6 for local-link traffic only since Verizon FiOS doesn’t provide me with IPv6 Internet connectivity (yet?).  What was happening is that my Nokia Lumia 928 Windows Phone 8 device was trying to use an IPv6 local-link only IP address to communicate with the Office 365 platform and this was causing the failure to connect”

Issue variations

The same issue appears to occur for users on some mobile data networks, while their local WiFi is fine. So it is the reverse situation described in this post. In this example you have no options to turn off IPv6, you are dependent on your mobile provider. The following forum thread illustrates this: The issue has nothing to do with GDR3/Black – it is solely with VZW’s network and how they handle IPv6 with Lumia phones.