Dahua offline after a new router? Start at the recorder
If DMSS stopped connecting immediately after a router or internet-provider change, record that timing before changing anything else. It is a useful clue, not proof that the router is the only cause.
1. Separate recording from remote access
At the recorder's local monitor, check whether live pictures and recent playback are available. Write down which cameras are affected. Working local pictures do not prove that the recorder can reach the internet.
2. Inspect the connection
Check power and the recorder's network cable. Note whether other devices on the same network have internet access. Do not factory-reset the recorder or delete the device from DMSS as your first step.
3. Compare the LAN settings
A recorder using an old static IP configuration may no longer match the replacement router. Photograph the existing settings for your own records before any change. Check the LAN IP, subnet mask, gateway and DNS against the current network. Do not change the internal PoE camera network by mistake.
If the installation is managed by an IT provider, ask them to check addressing. A controlled DHCP test can be appropriate on a simple network, but only with local access and a recovery plan: changing the recorder's address can interrupt integrations or remote access. Do not attempt it blindly from a remote-only connection.
4. Record the P2P status
Read the recorder's P2P status and the exact DMSS error. Dahua's official troubleshooting guidance starts with checking IP, gateway and DNS for changed network settings. Menu names vary by model and firmware. Avoid opening inbound ports, disabling a firewall or installing guessed firmware as a shortcut.
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Prepare the recorder model, exact error, whether local playback works, when the router changed and any checks already tried. Redact serial numbers, QR codes, public IP addresses and personal information from screenshots. Never send passwords.
Technical reference: https://dahuatech.zendesk.com/hc/en-gb/articles/12228822283666-IPC-NVR-XVR-P2P-Issues-Troubleshooting
CCTV Rescue is an independent service, not Dahua manufacturer support.
Also read: DMSS on WiFi but not mobile data.
Missing footage on the NVR? Read: Dahua NVR not recording — check playback, HDD and schedule.