Dahua IPC-HDW2449TM-S-IL intermittently returns RTSP 403 Forbidden ("online user amount has reached the threshold")

[ChrisJakis]

Hi,

I'm trying to troubleshoot an intermittent RTSP issue with Dahua cameras and would appreciate your advice.

Environment

Home Assistant OS (VM on Proxmox)
WebRTC Camera: 3.6.1
go2rtc: 1.9.9 (bundled with WebRTC Camera)

Cameras:

• 7x Dahua IPC-HDW2449TM-S-IL-0280B

• Firmware: V2.840.0000000.26.R Build 2026-02-25

• 1x Dahua DH-IPC-PDW3849-A180-AS-PV (this camera is almost never affected)

NVR:

• Dahua NVR4108-8P-4KS2

Symptoms

Randomly one or more cameras stop opening through go2rtc/WebRTC.
go2rtc logs show:

streams: wrong response on DESCRIBE

and after enabling trace logs I can see:

RTSP/1.0 403 Forbidden

At exactly the same time, when logging into the camera web interface, the camera reports:

"The online user amount has reached the threshold!"

According to Dahua specifications, the camera supports 6 simultaneous online users.

Configuration

Each camera has a single stream definition, for example:

kamera_front:
rtsp://admin:password@192.168.88.101:554/cam/realmonitor?channel=1&subtype=1

No multiple aliases or duplicate streams.

Things already tested

• #backchannel=0
• #input=rtsp/udp
• restarting Home Assistant
• restarting go2rtc
• checking active streams in go2rtc UI

go2rtc UI usually shows:

0 / info / probe / net

meaning there are no active producers or consumers.

Additional observations

• The problem started only a couple of months ago after expanding the system.
• The panoramic Dahua camera (different model) is almost never affected.
• The seven IPC-HDW2449TM-S-IL cameras are the ones showing the issue.
• Home Assistant also has the Dahua integration installed for events/sensors.
• No ONVIF integration is installed.
• Cameras have DHCP reservations (IPs never change).

Has anyone seen Dahua cameras returning RTSP 403 together with
"The online user amount has reached the threshold!"?

Is there any known incompatibility with this Dahua firmware or anything else I should capture in trace logs?

Thanks!