Hi there! I'm Evan. Feel free to check out my FL profile for technical specifics, but as a brief overview, I have been a third line Senior IT technician for around 7 years, and an IT Professional in the UK for a little over 10 years. Period to IT, I come from a North American customer service and hospitality background.
I am very well acquainted with Exchange and excel access via Active Sync and OWA, and should have no problems resolving your issue in less than an hour if your description is accurate. You're right in that it sounds like a DNS issue, or a small configuration issue, or a problem with bindings in IIS, or routing/NAT.
I could look at the issue tonight around 7pm UK time if that helps you?
As a bit of background about me of how interested:
My IT career is mostly geared around high level fault management and troubleshooting in Windows Domain environments along with associated networking and infrastructure (Servers, Routers, Switches, Desktops, Virtualization, Desktops, Laptops, WiFi, Mobile Phones, websites, Office 365, etc.). I also have plenty of experience with communicating issues to every level of the corporate structure (from the mail room to the Director's office), and tend to stick with a 'plain english' approach to diagnosis and assessment.
I'd be happy to discuss your specific project requirements in further detail via FL chat or A Skype call if you'd like to see if you think I can add value to your current support provision outside of this ad-hoc issue.
Looking forward to any feedback you might have about my bid, and hopefully to a great working relationship.
All the best,
Evan