UNABLE TO JOIN SESSION EVERYTIME I TRY MULTIPLAYER, PLEASE HELP

Hello,

Everytime time I try to join a multiplayer match it said unable to join session, I have tried everything, NAT open, all the ports open.

Please help. Thanks

UPDATE:

I fixed the problem, what I did was login in my ISP web page, sign in with my user and password, and in the options it was 1 called PROTECTION. It was actived by default, so I turned it off and it solved my problem.

I guess it was an option that my ISP provides for some kind of protection, its like the firewall in router configuration.

If anyone needs help or have a question this is my gamertag : RafaA07