I’m running the same lastest firmware, so my experience is that it’s not a problem with the firmware. There are some limitations for what can be set as the password, but cannot find that in any documentation. Try sending something simple like 11111. All else still failing crank up the Wireshark.
I have found the best way to deal with new functions on the Yealink phones is to create a config file for each type of firmware phone model and place it in the /usr/share/ombutel/www/includes/xepm/provision/
For your firmware the file would be y000000000029.cfg 29 being the the version of phone you are working with. For the T46S it woud be y000000000066.cfg etc… This is the firmware model number and will cover any versions like 29.81.X.X 29.83.X.X 29.84.X.X and so on.
This file can contain any funtions that are not covered by The Endpoint Manager and would apply to all phones of the model you are dealing with. Since the Endpoint manager only creates the mac.cfg file when the phone boots it will read both.
Your file can contain any funtions, in the example below you can see the warnings display mode can be disabled so you won’t see the default password warning icon, also a custom wallpaper or any autoprovision parameter, but must conain the first two lines as written.
##File header “#!version:220.127.116.11” can not be edited or deleted, and must be placed in the first line.##