Celullar data 3G won't work anymore like should after installing iOS7.1

I have a iPhone 5. I updated last week to iOS7.1.

My provider is Proximus in Belgium. I have a world data plan so I can use it everywhere. But sinds the update not anymore. When I go to another country celullar data does not work anymore. When I get back to Belgium I also don't get any data access. Then I have to reboot the phone and then it works again. But never on another network in an other country then Belgium. I did already a total reinstall of the iPhone and go back to factory settings but also that does not work. Calling the provider didn't helped also, everything is activated on my account. Apple? What did you do with the new iOS that those things doesn't work anymore!?? I travel alot for my work and I need my data always so this is a big problem for me!
Are there more people who have this problem?