What is your NAT as reported by the game? You can find this in the Gameplay section of your settings tab. It is listed under STUN type. Also what is your internal and external ports?

This means that something may be attempting to take over the ports that your PC is calling for in order for Destiny 2 to connect. Please reboot your modem and router to see if the issue subsides.

If the issue is persisting, then this could mean that your router is not properly configured for Destiny 2. If you are using port forwarding, this may mean that your PC’s IP has changed. Please review the Advanced Troubleshooting Guide, linked below, for more information and steps you could take to try and resolve this issue. https://help.bungie.net/hc/en-us/articles/360049496751-Advanced-Troubleshooting-UPnP-Port-Forwarding-and-NAT-Types