Solved Provision Grandstream GXP1615 Frustrating

[netgama]

This is suppose as simple as "Assign Extension" but its not working for me, after assign extension the phone still shows as "New" under Ext but if I try to assign extension again it says its already assign to the one its suppose to be assign, and when call the assign extension it doesnt ring, the phone is DHCP, basic local setup, no remote setup, 3CX version 18.0 (Build 461) , pls advice, thanks

 

[netgama]

Just to close this post, everything went smooth, change subnet and the phone was added on the first try, thx to everyone who took time to help me