Hey there, This error can be due to packet loss or disconnections between your home network and Bungie (such as ISP saturation or general internet congestion). It can even be caused by certain WiFi setups, or mobile hotspots that may have experienced a blip or loss of connection. Before proceeding any further, I strongly recommend switching from WiFi to a wired connection, at least temporarily. This is an important first troubleshooting step to rule out WiFi signal strength/stability as a possible culprit. If you're experiencing an issue where you repeatedly hit this error and cannot log into Destiny, please attempt to force quit Destiny by completely closing the game and relaunching Destiny to get out of this state. Let me know if you need any further assistance. Hope this helps!

Try closing out of your battle.net and signing out completely, then resign in. If that doesn't work maybe restarting your computer will do the trick. Go into task manager and see if anything is going on in the background too.