Dahua P2P offline: causes and checks
What the status means, the causes to check on the recorder and the site, and reaching the recorder without P2P.
Dahua P2P offline means the recorder is not connected to Dahua's P2P service, so apps that find it by its serial number cannot reach it. The usual causes are the P2P setting switched off, the recorder's network settings (DHCP, gateway or DNS), a cable or a line that blocks its outbound traffic, or the service itself.
Dahua's own checklist starts with the P2P setting, DHCP and DNS, then a ping test from the recorder. Most checks below are done at the recorder's own screen or its web page.
The recorder is not reaching Dahua's P2P service
With P2P, a Dahua recorder connects out to Dahua's service. Dahua's software, such as SmartPSS, can then add it by its serial number with the recorder's own username and password, instead of by an address. The status on the recorder's P2P page should read "Online".
"Offline" there means that connection is not up. The recorder may be working perfectly on the site's network: its cameras record and it answers on the local network. Only the path through Dahua's service is down.
The causes and how to check each
| Cause | How to check |
|---|---|
| P2P switched off | On the recorder, open Main Menu, Settings, Network, P2P, or Setup, Network, P2P on its web page. P2P must be enabled. The same page shows the status and the serial number. |
| Network cable or switch | Check the connection from the recorder to the router. In Dahua's ping test, a failed result points to the network cable first. |
| DHCP, gateway or DNS | Dahua's checklist has DHCP enabled, so the router gives the recorder its address, gateway and DNS. It lists 8.8.8.8 and 8.8.4.4 as the two DNS servers. A recorder given a fixed address by hand can have a wrong gateway or no DNS, so it cannot find the service by name. |
| Outbound traffic blocked | Run the ping test: Main Menu, Info, Network, Test, to 8.8.8.8 and then to google.com. If 8.8.8.8 answers and google.com does not, DNS is the problem. If neither answers, the recorder has no way out: the cable, the gateway, or a firewall on the site's network. |
| Wrong serial number or login in the app | Dahua lists checking the serial number and the recorder's username and password in the app. Scan the QR code on the recorder's P2P page to be sure of the serial. |
| The service itself | If recorders at several sites, with nothing in common but the maker, show offline at once, the problem is not at any one site. Nothing at the site will fix it; wait, and use another way in meanwhile. |
Sources: Dahua's wiki pages P2P troubleshoot checklist (last modified 16 March 2020), P2P troubleshoot (16 March 2016) and add a device via P2P (2 October 2024), all read 16 October 2026.
A short order of work
- Check P2P is enabled on the recorder.
- Check DHCP is on, or that a fixed address has the right gateway and DNS servers.
- Run the ping test to 8.8.8.8 and google.com.
- Once all of the above is right, reboot the recorder, as Dahua's checklist says, and read the P2P status again.
- If it is still offline and the ping test passes, check the serial number and login in the app, then whether other sites show the same.
Port forwarding is not the way round it on CGNAT
Dahua's wiki also describes port forwarding: a fixed address on the recorder, then forwarding rules on the router, usually for the HTTP port and the TCP port (dahuawiki.com, last modified 4 February 2020, read 16 October 2026). Dahua's checklist gives 37777 as the default TCP port.
That needs a public address at the site. Sites on 4G, 5G and Starlink are almost always behind CGNAT (carrier-grade NAT: the site shares a public address with many others, so nothing can be forwarded to it). There, port forwarding and dynamic DNS do not work. A router WAN address from 100.64.0.0 to 100.127.255.255, or a private address, means CGNAT. A forwarded port also puts the recorder's own login on the internet.
Reaching the recorder through a box at the site
A Relayant box is another way in that does not depend on P2P. It plugs into a LAN port of the site's router and connects out to Relayant over an encrypted WireGuard tunnel. Nothing is opened or forwarded on the router, so CGNAT makes no difference.
- The box finds the devices on the site's network and names the maker and model where it can.
- In the portal you choose the recorder and the ports your software needs, such as 37777. The relay reaches only those device-and-port pairs.
- The recorder gets one address and port on Relayant. It stays the same when the recorder changes address on the site's network.
- Only the internet addresses you list can reach it.
- Any monitoring software that connects to a recorder by address and port works with it.
We hold no device logins and do not sign in to the recorder; your software signs in as it does now. The box also checks every minute that the recorder answers. A vendor port such as 37777 is only checked for an open port, because it needs a login. See NVR offline for how those checks and alerts work.
P2P and the box do different jobs, and a site can have both. DMSS stays the owner's app on a phone. The box gives the control room a standing address and port that does not depend on the P2P service.
Product names belong to their owners.
Something in this guide is wrong or missing? Tell us: hello@relayant.net.