Iphone 5 - Internet problems. Whatsapp and skype connect but mail and safari don't

Situation: Iphone5 connects to the internet through a cyberoam captive portal and a wireless network.

When I type in my credentials to the portal, it tells me that I am connected and skype and whatsapp connect happily to the net. But mail, safari, podcasts can't connect. Safari returns the message: "Safari cannot open the page because you iPhone is not connected to the Internet"... while I am receiving whatapp messages...

I am guessing ports might have something to do with it but I haven't been able to find how to control those on the iphone.

Any help appreciated. Lily