If power cycling your equipment made the situation worse, then something on your router is not properly allowing the network traffic for Destiny 2 to flow correctly. Unfortunately, due to the complex nature of routers and the different makes and models that are out there, I would not be able to provide further guidance other than providing you with the help article above. Please note that port forwarding REQUIRES you either DHCP reserve your computer to the IP that you wish to have it set to or to set it to a static IP. This can vary depending on the router you have and what the router prefers from a settings perspective. Please contact your router's support team for further guidance on how to do so.