Friend can't join fireteam

I’m trying to get one of my friends WiserBuckle9410 to join my fireteam to play custom games. But whenever he tries to join a fireteam it gives him the following error. “Unable to join, you were unable to connect to the Fireteam. Please try again.” He doesn’t have any content restrictions setup and he has gold. And whenever I try to join his fireteam it doesn’t give me an option to join him which only happens with him and not my other friends. This is starting to annoy the both of us and he has considered getting rid of his Xbox because of this issue. Please help.

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> I’m trying to get one of my friends WiserBuckle9410 to join my fireteam to play custom games. But whenever he tries to join a fireteam it gives him the following error. “Unable to join, you were unable to connect to the Fireteam. Please try again.” He doesn’t have any content restrictions setup and he has gold. And whenever I try to join his fireteam it doesn’t give me an option to join him which only happens with him and not my other friends. This is starting to annoy the both of us and he has considered getting rid of his Xbox because of this issue. Please help.

What are your respective NAT types? Have either of you tried restarting your routers and/or hard resetting your Xboxes (hold power button down for 10 seconds)?

Such issues are normally a case of there being a problem in the connection between two players whixh are usually nothing to do with the game or XBL