cannot sync iphone with exchange 2003 server when on internal wifi

hi, I have an iphone 3 that used to sync with my exchange server when in the office.
I have since taken the sim card out and use the phone just for emails. The phone will sync when i am using a remote wifi. But wont on the internal office wifi.

On the so called activesync settings, i have the external IP in the server name.
Is it not working, because the phone is looking at the external site, from with in the external IP ?

it did work for a good few months internally with no sim. I just ocnfused.

many thanks
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MikeIT ProfessionalCommented:
Have you added any firewall or virus software recently?  Sounds like the connection is being rejected....
It's DNS most likely.

Olyou need to create a zone internally that points your mail servers external address to the local address of exchange.
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