Look trought the CLI and look for a filed called “disable gui”
Someone might have it turned off before.
Anyway, you are not loosing much. The GUI is a piece of bad engineering.
I will stay away from the GUI, and mine works fine.
Here is the setting:
Primary Time Server: IP Address = 0.0.0.0
Secondary Time Server: IP Address = 0.0.0.0
UTC Offset: Unknown
Disc Tone Frequency: 480 Hz (min) : 620 Hz (max)
Disconnect On/Off Time: 250 mSec(on) : 250 mSec(off)
Call Indication Tone = None(0)
Disable GUI = no(0) This is enabled