I recently had to format my computer. I reinstalled QB 2018 Pro. When I get to activation to open exiting file It will not connect to the internet

You must contact Support to request reactivation of your license. If they refuse to do so, you can use the trial version as a workaround.

Hi Greg1957. I'll be happy to guide you in the right direction. Based on the details you've shared, I suspect you may be experiencing system issues that are causing the internet issue. In order to troubleshoot this, I recommend using the QuickBooks Tool Hub. The QuickBooks Tool Hub is designed to help fix issues such as the one you've described above. Feel free to check out this article here that shows you how to effectively use the Tool Hub to your advantage.

 Let me know how you make out. I'll be a message away in case you need further assistance.