Hey KillyCZ, many here on the answers section also suffer from this dreaded error, here's some info I have found with other from the community:
1. The online servers are "Functional" in the sense that some users that have played the game before November 2017 can enter the online portion of the game and play with others, but anyone playing the game on the Xbox 360 side after November 2017 cannot go in, myself included.
2. The answers to this problem is unknown even to EA, after several online chats and call no one there know why this is happening, on the help page https://answers.ea.com/t5/Need-for-Speed-Rivals/bd-p/Need-for-Speed-Rivals states that the Xbox 360 servers are "DOWN", this could be the potential issue of new users trying to connect but EA's IT guys dont run said servers or know why they are down.
3. This problem will not go away until they either fix the server connectivity issue, flat out disconnected them for good, reset them or magic. At this point it's anyone's guess.
the best course of action is to open a help case and you yourself talking to a representative about the error and tell them that there are at least 10 people on the answers forum that are also unfortunately locked out of the Multiplayer portion of the game at least on the Xbox 360 side.
Best of luck.
