Option can be found in game settings.
Sometimes also helps (when both clients are running) going into offline mode on Steam and Uplay, then launching the game.
See here for instruction.
Players who are using AMD FX Series processors may experience FPS drops and freezes, especially with the FX-8350 model.
Please note that a good cooling solution is also recommended in order to avoid overheating issues, should you implement this workaround.
Having the game installed to a Windows Storage Space device can make the game get stuck on the splash screen. Install the game on a regular disk (not a Storage Space) for the startup to proceed.