We have a website running on port 80 on our network. Port 80 is forwarded outside of the network, and it is accessible through a URL that points to the IP or the IP itself.
However, inside the network, it is not possible to access the external domain/IP address. It's possible to use the local I.P. address. For example, the web server can be accessed by using 192.168.168.22:80, but not mydomain.com. Mydomain.com works from an external network.
This is likely due to a rule in SonicWall. We are using Sonicwall TZ 215 and I am not sure what rules would allow for this access.
Let me know if I need to provide more information. Currently, there is a rule set from WAN to LAN to allow it to be accessed out of the network. I have tried some other rules, but have not found what works.