I added another Xenon to my mesh of three, previously I have always used the Argon as the assist node but this time I used a Xenon. Mesh network was all working correctly at the time. All seemed OK until it asked for the mesh password which it then repeatedly said was incorrect. I tried many times after reboots, restarting the app etc but no dice. The first password I used could have been wrong. Eventually I went back to using the Argon as the assist device and it worked straight away.