Hi panda!
I'll tell you what I do whenever I get these kind of errors, hopefully this will work for you too:
1. Close Destiny
2. Turn off console
3. Unplug router/modem for 2 min
4. Plug in and wait another 2 min
5. Check internet connection with other devices like a phone or a computer
6. Open console and re-set your connection (LAN cable/Ethernet is better, from experience)
7. Lanch Destiny
If this doesn't work, then try clearing your cache:
Completely shut your console off,
Once the console is completely off, unplug the power cord from the back of the console and let sit for ~5 minutes. Plug the power cord back into the console and power it on. Re-launch Destiny
If all else fails, try to uninstall Destiny and re-download it
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