Server on Synology DSM 7.2.2 is Unreachable Despite All Network Checks Passing (Ports Open) #3585

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opened 2026-02-21 01:28:44 -05:00 by deekerman · 1 comment

deekerman commented

2026-02-21 01:28:44 -05:00

Owner

Originally created by @techjuicelab on GitHub (Aug 4, 2025).

Bug Description

Environment

Device: Synology NAS [PLACEHOLDER: e.g., DS920+]
OS: Synology DSM 7.2.2-72806 Update 1
Deployment: Synology Container Manager
RustDesk Server Image: rustdesk/rustdesk-server:latest
Docker Network Mode: host

Problem Summary & Diagnostic Evidence

My self-hosted RustDesk server, which was running perfectly, became completely unreachable immediately after I updated my Synology NAS to DSM version 7.2.2-72806.

This is not a standard configuration issue. The evidence points to a potential bug in the Synology DSM network stack.

Here are the contradictory facts:

Server is Running: The container logs show the hbbr and hbbs processes start successfully and are listening for connections without any errors.
Firewall is Disabled: The main Synology firewall has been completely disabled during testing.
Ports Are Confirmed OPEN: An external port checker confirms that all required ports are OPEN and accessible from the public internet. This proves that router port forwarding is working correctly.
External Network Test Fails: Connection tests from a completely separate external network (Cellular/5G data) also fail.

This presents a paradox: Network traffic can reach the NAS, but it is not being delivered to the listening process in the host-networked container. This strongly suggests a change within the DSM OS is preventing the host-networked container from receiving the packets.

Docker-compose.yml

services:
  hbbs:
    container_name: hbbs
    image: rustdesk/rustdesk-server:latest
    command: hbbs -r myNASserver.com
    volumes:
      - ./data:/root
    network_mode: host
    depends_on:
      - hbbr
    restart: always

  hbbr:
    container_name: hbbr
    image: rustdesk/rustdesk-server:latest
    command: hbbr
    volumes:
      - ./data:/root
    network_mode: host
    restart: always

### How to Reproduce

### **3. How to Reproduce (버그 재현 방법)**

개발자가 이 버그를 직접 겪어볼 수 있도록 순서를 안내하는 부분입니다. 'DSM을 특정 버전으로 업데이트한다'는 것이 핵심 단계임을 명시합니다.

```markdown
1.  Set up a RustDesk server on a Synology NAS running a version of DSM prior to 7.2.2, using `network_mode: host`.
2.  Confirm that the server is working correctly and clients can connect.
3.  Update the Synology NAS to DSM version `7.2.2-72806`.
4.  Attempt to connect to the RustDesk server from any client (internal or external).
5.  Observe that the connection fails, despite the server containers running and external port scans showing the ports are still open.

### Expected Behavior

The RustDesk client should be able to connect to the self-hosted server successfully after the DSM update, just as it did before the update.

### Operating system(s) on local (controlling) side and remote (controlled) side

Local (Controlling): Windows 11, macOS, iOS, iPadOS (multiple clients tested) Remote (Server): Synology DSM 7.2.2 (Connection fails at the server level)

### RustDesk Version(s) on local (controlling) side and remote (controlled) side

Local Client: 1.2.6 Remote Server: latest (Docker image version)

### Screenshots

<img width="693" height="546" alt="Image" src="https://github.com/user-attachments/assets/d3f61986-d649-4c6c-a9e1-df69be547bf2" />

### Additional Context

_No response_

Originally created by @techjuicelab on GitHub (Aug 4, 2025). ### Bug Description ### Environment - **Device:** Synology NAS [PLACEHOLDER: e.g., DS920+] - **OS:** Synology DSM 7.2.2-72806 Update 1 - **Deployment:** Synology Container Manager - **RustDesk Server Image:** `rustdesk/rustdesk-server:latest` - **Docker Network Mode:** `host` ### Problem Summary & Diagnostic Evidence My self-hosted RustDesk server, which was running perfectly, became completely unreachable immediately after I updated my Synology NAS to DSM version 7.2.2-72806. This is not a standard configuration issue. The evidence points to a potential bug in the Synology DSM network stack. **Here are the contradictory facts:** 1. **Server is Running:** The container logs show the `hbbr` and `hbbs` processes start successfully and are listening for connections without any errors. 2. **Firewall is Disabled:** The main Synology firewall has been **completely disabled** during testing. 3. **Ports Are Confirmed OPEN:** An external port checker **confirms that all required ports are OPEN** and accessible from the public internet. This proves that router port forwarding is working correctly. 4. **External Network Test Fails:** Connection tests from a completely separate external network (Cellular/5G data) also fail. This presents a paradox: **Network traffic can reach the NAS, but it is not being delivered to the listening process in the host-networked container.** This strongly suggests a change within the DSM OS is preventing the host-networked container from receiving the packets. ### Docker-compose.yml ```yaml services: hbbs: container_name: hbbs image: rustdesk/rustdesk-server:latest command: hbbs -r myNASserver.com volumes: - ./data:/root network_mode: host depends_on: - hbbr restart: always hbbr: container_name: hbbr image: rustdesk/rustdesk-server:latest command: hbbr volumes: - ./data:/root network_mode: host restart: always ### How to Reproduce ### **3. How to Reproduce (버그 재현 방법)** 개발자가 이 버그를 직접 겪어볼 수 있도록 순서를 안내하는 부분입니다. 'DSM을 특정 버전으로 업데이트한다'는 것이 핵심 단계임을 명시합니다. ```markdown 1. Set up a RustDesk server on a Synology NAS running a version of DSM prior to 7.2.2, using `network_mode: host`. 2. Confirm that the server is working correctly and clients can connect. 3. Update the Synology NAS to DSM version `7.2.2-72806`. 4. Attempt to connect to the RustDesk server from any client (internal or external). 5. Observe that the connection fails, despite the server containers running and external port scans showing the ports are still open. ### Expected Behavior The RustDesk client should be able to connect to the self-hosted server successfully after the DSM update, just as it did before the update. ### Operating system(s) on local (controlling) side and remote (controlled) side Local (Controlling): Windows 11, macOS, iOS, iPadOS (multiple clients tested) Remote (Server): Synology DSM 7.2.2 (Connection fails at the server level) ### RustDesk Version(s) on local (controlling) side and remote (controlled) side Local Client: 1.2.6 Remote Server: latest (Docker image version) ### Screenshots <img width="693" height="546" alt="Image" src="https://github.com/user-attachments/assets/d3f61986-d649-4c6c-a9e1-df69be547bf2" /> ### Additional Context _No response_