Repair Dahua VTO-VTH Link

My VTO33110 door station refuses to discover the VTH indoor monitor, and inside the DMSS app the VTH is permanently tagged “offline.” Both devices sit on the same wired network, yet they still will not register with one another. I need a Dahua-savvy technician to log in remotely, review the current IP addressing, SIP server details, and any required port-forwarding or multicast settings, then adjust whatever is out of place so the VTO can ring the VTH and the DMSS app shows the monitor online. Acceptance criteria • VTO successfully calls the VTH and video/audio works in both directions. • DMSS lists the VTH as online and receives door station calls. Please be comfortable using Dahua ConfigTool, SmartPSS, or similar utilities and be ready to walk me through any physical resets or firmware tweaks if they become necessary.