There is a special mechanism about 3CX server provision the DSS key on UC46.
If you provision one or more DSS key on UC46 then the PC port setting on 3CX template will be set to "Connect to Expansion Module".
And If you didn't provision any DSS key on UC46 and then the PC Port setting on 3CX template still is "bridge". In this time, if you modify the PC port setting on phone webpage to "Connect to Expansion Module".The phone will restart and get the configuration from 3CX server. The setting of PC port will be set to "bridge" again.
For example:
UC926 have 36 line keys. If you provison the 37th DSSkey on 3CX webUI. And then restat or re-provision the phone. The PC port setting will be set to "Connect to Expansion Module" automatically.
If you modify the PC port setting on UC926 webpage to "Connect to Expansion Module".UC926 will restart and get the configuration from 3CX server. The setting of PC port will be set to "bridge" again.