Try changing the IP with a digital phone and integrate it to your actual network, most of the times this works.
How to change IP via phone:
Press Transfer
Press 800
Press passcode, default is 4321
Press volume up to change Disable to Enable
Press Transfer
Program mode via phone is now enabled
Press Transfer
Press 830
fill in the IP, navigate with volume buttons and the right key of the buttons directly under the screen
Press Transfer when selected yes on reboot.