Slow Outlook Sync Z10

I'm having an inexplicable issue with outlook (Office 365) syncing on the Z10.

My dad and I both work at our family business, and since last week we stopped our local server and installed Microsoft Office 365. We both bought the Z10 three weeks ago (finally convinced my dad to switch from the iPhone to BB ;) ) and with the installation of Office 365 here at the office, we started adding our outlook accounts to our Z10 phones.

And here's the strange thing: my account on my Z10 works perfect. Both email, contacts, calendar, ... are synced within 5 seconds. But on the Z10 of my dad - with exactly the same settings, the same data plan, ... - it does not work perfect. When he receives an email in outlook, it takes about 10 to 15 minutes before he receives it on his Z10. The same with calendar topics... I've been looking for three days now, in all the settings, searching online, looking at the outlook settings etc. Everything on my dad his Z10 is the same as on mine, and yet, he has the issues...

Does anyone has experienced the same issues? Anyone has a possible answer what could cause these issues? I hope that the CrackBerry nation can help me out, I'd really like to avoid the "Well, it worked perfectly on my iPhone" sentence...

Thanks in advance,



G.