Outlook Web Access

try - https://owa.domainname/exchange/logon.asp

where domain name is your full domain e.g. "america.com"

hopefully this will work

If you are going through a Firewall, then there are certain ports that need to be opened and configured on the Exchange server. See technet article Q259240 for more details.

I'm not sure if you are using the ip shown above as just an example. But if this is your exchange server's actual ip then there is a problem as it is a non-routable ip address and cannot be accessed over the Internet.
If the server has a routable ip but is behind a firewall then you will have to open the port where your IIS web server is running, which by default is 80.

Answer3 is correct. 192.168.1.1 is a non-routable Class C IP address. It is reserved for interal office use. You are not the only people using 192.168.x.x for interal office stuff.
What you need to find out is what your external static IP address(es) is/are. If you can map (via NAT, most likely) an external IP to the 192.168.1.1, then you could connect.
For example, if you have IP address 4.17.209.25 (if it is assigned to you by your ISP), then you could have it routed to 192.168.1.1. 4.17.209.25 is a valid IP address on the Internet; it is not reserved.
So, you need to find out how you are set up externally, then point an IP to the server. You should then set up some port filtering on a firewall (assuming you have one), so that only port 80 on IP 4.17.209.25 (again, the example IP; yours will be different) points to port 80 on 192.168.1.1

Call your ISP on this. They will help.

hope this helps

The IP Range 192.168.1.1 was only an example. I actually use the IP of the mailhost provided by the server. Didn't want to display it until firewalls, etc were in place.

I think the router is broken, and have ordered a replacement. It has wiped passwords, and we cannot alter any ports at all.