networking - Unable to use FQDN when using local network (Ubuntu Server 10.04, dd-wrt)

Networking newb here... I seem to be having an odd networking issue.

When I am using a PC/laptop/Smart phone on my local network I am unable to access web pages (or email) on my network server using the FQDN.

Here's the set-up:

• Domain name provider that points to the static IP address e.g. example.com points to 222.111.111.001


• Fixed IP router address: e.g. 222.111.111.001


• dd-wrt router: 192.168.1.1 It has port-forwarding to the Ubuntu server which seems to work as it serves pages, etc to non-local ip addresses. Local machines are issued ip address via DHCP in the 192.168.1.100 to 149 range.


• Ubuntu 10.04 server on 192.168.1.150


• Clients include Linux mint machines, Android phone and get addresses such as 192.168.1.104

If I am on a client on the local network ( 192.168.1.104) and I try to navigate to a webpage on example.com/index.htm then the request times out.
The same sort of thing applies to email - If I am connected on the local network (wirelessly) then I cannot access the IMAP and SMTP servers using mail.example.com

The situation is fine if I am using a non-local network (e.g. my Vodafone mobile network). The device will successfully load example.com/index.htm
The situation is also ok if I navigate to 192.168.1.150/index.htm

Any thoughts on how to trouble shoot this one?
It's obviously a little annoying...

Cheers.