NAT (Network Address Translation) Loopback constraints are due to security measures associated with a router. When attempting to log in to a web based application from inside a network using a URL that contains an external IP address you may receive an error message due to NAT loopback. Quite often the fix can be as simple is flipping on switch on the router to "enable NAT loopback". If your router does not support NAT Loopback, we have identified some other options that will allow you and your customer to connect to the web application successfully.
Modify Hosts File
The Hosts file maps the host names of sites to their corresponding IP addresses. By adding new entries into the Hosts file, you may be able to circumvent the NAT loopback.
Use an Internal IP Address or Computer Name URL
This allows each party to use a different URL to connect to the software. The URL you use will only be recognizable inside your network so be aware to change the address when you send email invitations or when you create an unattended session (as these features by default will use the URL in your browser).
Create a Subdomain
By creating a subdomain you are connecting to an external domain. Since the domain is hosted outside your network it should eliminate the problems with NAT loopback.
If you have a static IP address, you may create a subdomain of your existing domain and configure it to point at the IP address of your ScreenConnect server. If you have a dynamic IP address, you need to use a dynamic DNS account, which can be created at sites such as Dyn.com and no-ip.com.
Select a New Router
Check router specifications or call to see whether it supports NAT loopback.
For a more in-depth rundown into these solutions please refer to our knowlegdge article on NAT Loopback.