T20P Register Fail on Reboot

[amirscei]

Hi All! I'm new here and I would really appreciate if someone could help me with this.
We have at least 50 Yealink T20P IP Phones and some of them are acting very weird. Sometimes, when there's a power interruption, once the unit reboots, it won't be able to register on the phone server. I have to disable Account 1 and enable registration on Account 2 in order for the phone to work again. The main point is, every time the phones reboot, they can't register. Checked the Firmaware and it's updated. at least 10 out of 50 phones are acting like this. Need help urgently! thanks in advance!