Hello,
We offer instructions on how to reconnect a camera to the network after a router change on our Support Forum at this link.
If those steps fail, it is suggested to power down your device, remove it from your Alarm.com account, complete a factory reset of the camera, then connect the device using the normal procedures.
ADC-V721W
Hold Reset button until LED rapidly flashes red and green, which usually happened after 15 seconds. Same as the WPS button, which is on the back of the camera.
ADC-V521IR
Press and hold the Reset button until the LED alternates flashing red and green, which usually happens after 10-15 seconds. The Reset button can be found on the back of the camera.
Please let me know if you continue to have troubles or have questions about anything else.