Thanks for your posting! Sure, happy to help with your question.
The problem is that you are trying to connect from a TestRail Cloud account to JIRA that is installed on your private network. For the full push/lookup integration TestRail needs to be able to connect to JIRA. If this is installed on your private server behind a firewall, then such a connection isn’t directly possible out of the box. To use the full integration, you would have the following options:
Make JIRA available for connections over the Internet (I recommend talking to your IT team for this; we can also provide the IP addresses of our servers so you only need to approve our IPs for connections)
You can also install TestRail on your own local server and we can provide the necessary details for this
If you just want to try the full integration for now, you could maybe also temporarily set up a hosted trial version of JIRA just to try the integration: https://www.atlassian.com/software/jira/try
Please note that this only affects the Push & Lookup feature and the JIRA add-on can still be installed and used:
I hope this helps!