My wife and I have been having this issue for a while now and this works for us on PS4 that is. 1. Both turn off (not rest mode) console AT THE SAME EXACT TIME 2. Turn on Console 3. Open Destiny 4. Pick character THEN IMMEDIATELY 5. Have one join the other. Step 5 is crucially because even a good 5 second delay inbetween joining will make you repeat the process. It seems Bungie's servers don't realize you are on the same network the first couple of seconds yall log on. "60% of the time, it works everytime"