Hello there, PTI Phil.

I appreciate you for coming back to the thread and clarifying your concern about setting up your company firewall to operate QuickBooks smoothly. Let me route you to the right person to assist you further on this matter to avoid getting unexpected errors on your end.

As mentioned by my peer above, QuickBooks doesn't need particular IP addresses or servers for the license to sync. However, to verify what servers are so you can allow access to them through your company firewall, I recommend consulting an IT expert. They have the tools to check and provide the specific server you need to use and their Fully Qualified Domain Names (FQDN) to configure your company firewall. 

In case you need steps on how you can fix an error that says QuickBooks stopped working, you can read this article: QuickBooks Desktop won't open.

Please let me know if there's anything else you need or questions about managing or running QuickBooks Desktop. I'm always ready to help you further, PTI Phil. Take care!