Stupid question, did you try playing before opening ports? And did you have a noticeable problem.
Have you run a NAT/Internet/Connection test on your console? What were the results.
If you enable UPNP on the netgear 7550 then you wont need to worry about any ports being forwarded it will take care of it.
And per »
www.bungie.net/en/Help/A ··· le/11931 only port 3074 UDP is required inbound.