I have been unable to get online with Forza5 since updating to the New Xbox One Experience.
Anyone else having this problem or know of a solution?
The solution is to read the information on the latest beta release Forza 5 for KNOWN ISSUES:
“You may be unable to join multiplayer matches in Forza 5.”
As far as beta participants are concerned, no “work-around” is offered. It is as it is.