Player issue, not Bungie servers since there are none that determine player connections. Hit detection is purely Peer-to-Peer. Player Ping also is determined by Framerate. So someone can be on a low-quality laptop and connect well in orbit since there's nothing happening and then eat dirt when the match starts because they can't hold more than 15fps. Also lag switches, etc. Also cross-platform and cross-region fireteams exist to throw another wrench into the connection issue.