I have a different SP for each physical port. I.e. SP1, SP2, SP3, SP4 etc. For each phone, i select a different SP. I.e. for phone1 = SP1, phone2 = SP2.
I keep programming it and every time I reboot the system, only phone2 reverts back to SP1. The other ports are working fine. I uncheck the default, but it reverts back to default.
IMPORTANT NOTE: I do not use the web to program my devices. I have a local PC and I enter the local IP address directly to the device.