80072efd error while syncing exchange mails

[WPCentral Question]

Hi,

I have a Nokia Lumia 520.
While syncing mails from my corporate exchange client, the following error comes up:

We are having a problem connecting to the server.
Error code: 80072EFD.

This happens only on wifi, not on 3g.
This happens only for exchange, not for google mail.

I have reconfigured the server to m.outlook365.com, but it does not help.
I am not prepared to disable IPV6 on my home router, in any case I cant do it on my office wireless network.

Please help me, else I will have to return this phone.

Regards
Punit