diff --git a/docs/configuring-playbook-synology.md b/docs/configuring-playbook-synology.md
index 7a90bd1c0..9a3d2e33a 100644
--- a/docs/configuring-playbook-synology.md
+++ b/docs/configuring-playbook-synology.md
@@ -23,20 +23,33 @@ This document is a guide for preparing Synology DSM for the installation of the
 The playbook automatically detects Synology DSM by checking for `/etc/synoinfo.conf`. When detected, it:
 
 - Uses `synouser` and `synogroup` (DSM-native tools) instead of standard Linux user management
-- Pins the Python `requests` package to a version compatible with the Docker SDK
+- Constrains the Python `requests` package to a version compatible with the Docker SDK
+- Ensures `/volume1` has shared mount propagation so container bind mounts work correctly
 - Deploys a `matrix-synology-boot-fix` service that runs on every boot after Docker is ready
 
+You can override auto-detection by setting `matrix_base_host_is_synology: true` or `false` in your `vars.yml`.
+
+### Matrix Service Account
+
+The playbook creates a `matrix` system account using Synology's `synouser` tool. The account is secured as follows:
+
+- **Expired** (`expired=1`) — the account cannot be used to log in to DSM or any application
+
+You must set a password for this account via `matrix_synology_user_password` in your `vars.yml` (see [vars.yml Configuration](#varsyml-configuration)). The password cannot be used to log in because the account is expired, but a non-empty password is required as an additional security layer.
+
+> If you pre-create the `matrix` user manually before running the playbook, the playbook will not modify the existing account's settings — you are responsible for securing it.
+
 ### Boot-fix Service
 
 Synology DSM has two boot-time quirks that the boot-fix service addresses automatically:
 
 **1. `/volume1` shared mount propagation**
 
-Docker requires `/volume1` to be mounted as shared (`mount --make-shared /volume1`) for container bind mounts with `bind-propagation=slave` to work correctly (used by matrix-synapse for its media store). On Synology, this cannot be inserted into the systemd chain before Container Manager starts — doing so causes Container Manager to detect a broken dependency and prompt for repair on every boot. The boot-fix service runs this command after Docker is already up, safely outside Container Manager's dependency chain.
+Docker requires `/volume1` to be mounted as shared (`mount --make-shared /volume1`) for container bind mounts with `bind-propagation=slave` to work correctly (used by matrix-synapse for its media store). On Synology, this cannot be inserted into the systemd chain before Container Manager starts — doing so causes Container Manager to detect a broken dependency and prompt for repair on every boot. The playbook applies this during setup, and the boot-fix service re-applies it on every subsequent reboot, safely outside Container Manager's dependency chain.
 
 **2. Skipped services at boot**
 
-Synology's systemd drops services with multi-level dependency chains from the boot activation queue (e.g. `matrix-traefik → matrix-container-socket-proxy → docker`). These services show as `inactive (dead)` after reboot even though they are enabled. The boot-fix service scans for any enabled `matrix-*.service` that is still inactive after boot and starts them automatically.
+Synology's systemd drops services with multi-level dependency chains from the boot activation queue (e.g. `matrix-traefik → matrix-container-socket-proxy → docker`). These services show as `inactive` or `failed` after reboot even though they are enabled. The boot-fix service scans for any enabled `matrix-*.service` in either state and starts them automatically.
 
 > **If you previously configured a Task Scheduler entry** (`Control Panel > Task Scheduler`) to run `mount --make-shared /volume1` at boot-up, you can remove it — the boot-fix service now handles this.
 
@@ -76,7 +89,8 @@ mkdir ~/path/to/your/project/folder
 cd ~/path/to/your/project/folder
 
 python3 -m venv ./myenv
-source ./myenv/bin/activate
+# (optional) activate python virtual environment
+# source ./myenv/bin/activate
 ```
 
 ## Inventory Configuration
@@ -84,8 +98,8 @@ source ./myenv/bin/activate
 In your `inventory/hosts` file, set the Python interpreter to your virtual environment:
 
 ```ini
-# SSH key authentication example
-matrix.example.com ansible_host=<your-dsm-ip> ansible_ssh_user=<dsm-ssh-user> become=true become_user=root ansible_python_interpreter=/absolute/path/to/myenv/bin/python ansible_sudo_pass='your-password'
+# SSH key authentication with empty passphrase example
+matrix.example.com ansible_host=<your-dsm-ip> ansible_ssh_user=<dsm-ssh-user> become=true become_user=root ansible_python_interpreter=/volume1/homes/path/to/your/project/folder/myenv/bin/python ansible_sudo_pass='your-password'
 ```
 
 ## vars.yml Configuration
@@ -95,6 +109,14 @@ Add the following Synology-specific variables to your `vars.yml`:
 ```yaml
 # Synology-specific settings
 
+# Controls Synology DSM-specific handling. `null` means autodetect (via /etc/synoinfo.conf).
+# Set to `true`/`false` to force.
+# matrix_base_host_is_synology: true
+
+# Password for the Matrix service account created by the playbook.
+# The account is created as expired so this password cannot be used to log in.
+matrix_synology_user_password: "your-strong-password"
+
 # User and group that will be created automatically by the playbook
 matrix_user_name: "matrix"
 matrix_group_name: "matrix"
@@ -104,7 +126,7 @@ matrix_base_data_path: "/volume1/docker/matrix"
 
 # Use Synology Container Manager's Docker daemon instead of installing Docker
 matrix_playbook_docker_installation_enabled: false
-devture_systemd_docker_base_host_command_docker: "/usr/local/bin/docker"
+devture_systemd_docker_base_host_command_docker: "/var/packages/ContainerManager/target/usr/bin/docker"
 devture_systemd_docker_base_docker_service_name: "pkg-ContainerManager-dockerd.service"
 
 # Use Synology's NTP service
@@ -128,17 +150,12 @@ matrix_playbook_public_matrix_federation_api_traefik_entrypoint_config_custom:
 
 ## Running the Playbook
 
-Before running the playbook for the first time, run this once manually to ensure `/volume1` has shared mount propagation for the initial setup:
-
 ```shell
-sudo mount --make-shared /volume1
-```
-
-After the playbook runs, this is handled automatically on every subsequent boot by the `matrix-synology-boot-fix` service.
+# Full setup
+ansible-playbook -i inventory/hosts setup.yml --tags=setup-all
 
-```shell
-# Full setup and start
-ansible-playbook -i inventory/hosts setup.yml --tags=setup-all,start
+# start
+ansible-playbook -i inventory/hosts setup.yml --tags=install-all,start
 
 # Stop all services
 ansible-playbook -i inventory/hosts setup.yml --tags=stop
diff --git a/roles/custom/matrix-base/defaults/main.yml b/roles/custom/matrix-base/defaults/main.yml
index fd4eed773..aeca3512c 100644
--- a/roles/custom/matrix-base/defaults/main.yml
+++ b/roles/custom/matrix-base/defaults/main.yml
@@ -195,6 +195,21 @@ matrix_group_system: true
 matrix_user_uid: ~
 matrix_user_gid: ~
 
+# Controls Synology DSM-specific handling. `null` means autodetect (via /etc/synoinfo.conf).
+# Set to `true`/`false` to force.
+matrix_base_host_is_synology: ~
+
+# Password for the Matrix service account on Synology DSM.
+# Must be set to a non-empty value in your vars.yml when running on Synology.
+# The account is created as expired so the password cannot be used to log in.
+matrix_synology_user_password: ""
+
+# Version constraint for the requests Python package installed on Synology hosts.
+# requests >= 2.32 dropped the http+docker URL scheme used by the Docker SDK,
+# causing "Not supported URL scheme http+docker" errors. Installed into the
+# system Python interpreter (ansible_python_interpreter) on the remote host.
+matrix_base_synology_requests_version_constraint: "requests<2.32"
+
 matrix_base_data_path: "/matrix"
 matrix_base_data_path_mode: "750"
 
diff --git a/roles/custom/matrix-base/tasks/detect_platform.yml b/roles/custom/matrix-base/tasks/detect_platform.yml
new file mode 100644
index 000000000..5d36f3d89
--- /dev/null
+++ b/roles/custom/matrix-base/tasks/detect_platform.yml
@@ -0,0 +1,16 @@
+# SPDX-FileCopyrightText: 2026 Chiu Ki Sit
+#
+# SPDX-License-Identifier: AGPL-3.0-or-later
+
+---
+
+- name: Detect Synology DSM
+  ansible.builtin.stat:
+    path: /etc/synoinfo.conf
+  register: matrix_base_synoinfo_conf_stat
+  when: matrix_base_host_is_synology is none
+
+- name: Set matrix_base_host_is_synology from detection
+  ansible.builtin.set_fact:
+    matrix_base_host_is_synology: "{{ matrix_base_synoinfo_conf_stat.stat.exists }}"
+  when: matrix_base_host_is_synology is none
diff --git a/roles/custom/matrix-base/tasks/main.yml b/roles/custom/matrix-base/tasks/main.yml
index 86f8d9299..14c1340ab 100644
--- a/roles/custom/matrix-base/tasks/main.yml
+++ b/roles/custom/matrix-base/tasks/main.yml
@@ -16,6 +16,11 @@
   block:
     - ansible.builtin.include_tasks: "{{ role_path }}/tasks/validate_config.yml"
 
+- tags:
+    - always
+  block:
+    - ansible.builtin.include_tasks: "{{ role_path }}/tasks/detect_platform.yml"
+
 # This needs to always run, because it populates `matrix_user_uid` and `matrix_user_gid`,
 # which are required by many other roles.
 - tags:
@@ -30,7 +35,7 @@
     - install-all
   block:
     - ansible.builtin.include_tasks: "{{ role_path }}/tasks/setup_synology_prerequisites.yml"
-      when: matrix_synoinfo_conf_stat.stat.exists | bool
+      when: matrix_base_host_is_synology
 
 - tags:
     - setup-all
diff --git a/roles/custom/matrix-base/tasks/setup_matrix_base.yml b/roles/custom/matrix-base/tasks/setup_matrix_base.yml
index 017f98e5c..7fc7148e7 100644
--- a/roles/custom/matrix-base/tasks/setup_matrix_base.yml
+++ b/roles/custom/matrix-base/tasks/setup_matrix_base.yml
@@ -13,6 +13,14 @@
 
 ---
 
+# Snapshot ownership before any changes so we can decide whether a recursive
+# chown is needed (only when uid/gid actually differs from expected).
+- name: Check current ownership of Matrix base path (Synology)
+  ansible.builtin.stat:
+    path: "{{ matrix_base_data_path }}"
+  register: matrix_base_data_path_stat
+  when: matrix_base_host_is_synology
+
 - name: Ensure Matrix base paths exists
   ansible.builtin.file:
     path: "{{ item }}"
@@ -30,11 +38,17 @@
     dest: "{{ matrix_bin_path }}/remove-all"
     mode: '0750'
 
+# On Synology, name-based chown works for directly-touched paths but leaves
+# existing sub-paths with stale numeric ownership when uid/gid changes between
+# runs. We recurse only when the pre-task uid/gid didn't match, so normal runs
+# skip the expensive tree walk entirely. chown -R is used instead of the file
+# module's recurse option to avoid Ansible iterating every entry in Python.
 - name: Ensure Matrix base path ownership is correct using numeric UID/GID (Synology)
-  ansible.builtin.file:
-    path: "{{ matrix_base_data_path }}"
-    owner: "{{ matrix_user_uid }}"
-    group: "{{ matrix_user_gid }}"
-    recurse: true
-    state: directory
-  when: matrix_synoinfo_conf_stat.stat.exists | bool
+  ansible.builtin.command: chown -R {{ matrix_user_uid }}:{{ matrix_user_gid }} {{ matrix_base_data_path }}
+  changed_when: true
+  when: >-
+    matrix_base_host_is_synology and (
+      not matrix_base_data_path_stat.stat.exists or
+      matrix_base_data_path_stat.stat.uid | int != matrix_user_uid | int or
+      matrix_base_data_path_stat.stat.gid | int != matrix_user_gid | int
+    )
diff --git a/roles/custom/matrix-base/tasks/setup_matrix_user.yml b/roles/custom/matrix-base/tasks/setup_matrix_user.yml
index 219e3c1f3..2ab8a496c 100644
--- a/roles/custom/matrix-base/tasks/setup_matrix_user.yml
+++ b/roles/custom/matrix-base/tasks/setup_matrix_user.yml
@@ -6,13 +6,8 @@
 
 ---
 
-- name: Check for Synology DSM
-  ansible.builtin.stat:
-    path: /etc/synoinfo.conf
-  register: matrix_synoinfo_conf_stat
-
 - ansible.builtin.include_tasks: "{{ role_path }}/tasks/setup_matrix_user_synology.yml"
-  when: matrix_synoinfo_conf_stat.stat.exists | bool
+  when: matrix_base_host_is_synology
 
 - ansible.builtin.include_tasks: "{{ role_path }}/tasks/setup_matrix_user_linux.yml"
-  when: not (matrix_synoinfo_conf_stat.stat.exists | bool)
+  when: not matrix_base_host_is_synology
diff --git a/roles/custom/matrix-base/tasks/setup_matrix_user_synology.yml b/roles/custom/matrix-base/tasks/setup_matrix_user_synology.yml
index 079d67be6..6d49c9d7f 100644
--- a/roles/custom/matrix-base/tasks/setup_matrix_user_synology.yml
+++ b/roles/custom/matrix-base/tasks/setup_matrix_user_synology.yml
@@ -4,16 +4,36 @@
 
 ---
 
+- name: Fail if matrix_synology_user_password is not set
+  ansible.builtin.fail:
+    msg: >-
+      You must set `matrix_synology_user_password` to a non-empty value in your vars.yml.
+      This password secures the Matrix service account on Synology DSM.
+      The account is created as expired so the password cannot be used to log in.
+  when: matrix_synology_user_password == '' or matrix_synology_user_password is none
+
 - name: Check if Matrix user exists (Synology)
   ansible.builtin.command: id {{ matrix_user_name }}
   register: matrix_user_check
   changed_when: false
   failed_when: false
 
+# Created with expired=1 (cannot log in)
+# as this is a service account. If you pre-create the user, you are responsible
+# for securing it; the playbook will not modify an existing account's settings.
 - name: Ensure Matrix user is created (Synology)
-  ansible.builtin.command: /usr/syno/sbin/synouser --add {{ matrix_user_name }} "" "{{ matrix_user_name }}" 0 "" ""
+  ansible.builtin.command: >
+    /usr/syno/sbin/synouser --add {{ matrix_user_name }}
+    "{{ matrix_synology_user_password }}" "{{ matrix_user_name }}" 1 "" 0
   when: matrix_user_check.rc != 0
   changed_when: true
+  no_log: true
+
+- name: Ensure Matrix user password is up to date (Synology)
+  ansible.builtin.command: /usr/syno/sbin/synouser --setpw {{ matrix_user_name }} "{{ matrix_synology_user_password }}"
+  when: matrix_user_check.rc == 0
+  changed_when: false
+  no_log: true
 
 - name: Check if Matrix group exists (Synology)
   ansible.builtin.command: /usr/syno/sbin/synogroup --get {{ matrix_group_name }}
@@ -31,16 +51,19 @@
   register: matrix_user_uid_result
   changed_when: false
 
-- name: Get Matrix group GID (Synology)
-  ansible.builtin.command:
-    argv:
-      - python3
-      - -c
-      - "import grp; print(grp.getgrnam('{{ matrix_group_name }}').gr_gid)"
-  register: matrix_user_gid_result
+- name: Get Matrix group info (Synology)
+  ansible.builtin.command: /usr/syno/sbin/synogroup --get {{ matrix_group_name }}
+  register: matrix_synogroup_result
   changed_when: false
 
 - name: Initialize matrix_user_uid and matrix_user_gid
   ansible.builtin.set_fact:
     matrix_user_uid: "{{ matrix_user_uid_result.stdout }}"
-    matrix_user_gid: "{{ matrix_user_gid_result.stdout }}"
+    matrix_user_gid: >-
+      {{
+        matrix_synogroup_result.stdout_lines
+        | select('match', '^Group ID:')
+        | first
+        | regex_search('\[(\d+)\]', '\1')
+        | first
+      }}
diff --git a/roles/custom/matrix-base/tasks/setup_synology_prerequisites.yml b/roles/custom/matrix-base/tasks/setup_synology_prerequisites.yml
index 1589d639b..6d473fc2a 100644
--- a/roles/custom/matrix-base/tasks/setup_synology_prerequisites.yml
+++ b/roles/custom/matrix-base/tasks/setup_synology_prerequisites.yml
@@ -4,9 +4,15 @@
 
 ---
 
-- name: Ensure requests Python package is pinned for Docker SDK compatibility (Synology)
+- name: Ensure requests Python package is constrained for Docker SDK compatibility (Synology)
   ansible.builtin.pip:
-    name: requests==2.31.0
+    name: "{{ matrix_base_synology_requests_version_constraint }}"
     state: present
 
+# Run immediately during setup so matrix services can start without a manual
+# step. The boot-fix service handles this on every subsequent reboot.
+- name: Ensure /volume1 has shared mount propagation (Synology)
+  ansible.builtin.command: mount --make-shared /volume1
+  changed_when: false
+
 - ansible.builtin.include_tasks: "{{ role_path }}/tasks/setup_synology_boot_fix.yml"
diff --git a/roles/custom/matrix-base/templates/bin/matrix-synology-boot-fix.j2 b/roles/custom/matrix-base/templates/bin/matrix-synology-boot-fix.j2
old mode 100755
new mode 100644
index e852e8622..37d5d978b
--- a/roles/custom/matrix-base/templates/bin/matrix-synology-boot-fix.j2
+++ b/roles/custom/matrix-base/templates/bin/matrix-synology-boot-fix.j2
@@ -22,12 +22,12 @@
 # Wait up to 120s for Docker to be ready
 i=0
 while [ "$i" -lt 60 ]; do
-    /usr/local/bin/docker info >/dev/null 2>&1 && break
+    {{ devture_systemd_docker_base_host_command_docker }} info >/dev/null 2>&1 && break
     i=$((i + 1))
     sleep 2
 done
 
-if ! /usr/local/bin/docker info >/dev/null 2>&1; then
+if ! {{ devture_systemd_docker_base_host_command_docker }} info >/dev/null 2>&1; then
     echo "matrix-synology-boot-fix: Docker not ready after 120s, aborting" >&2
     exit 1
 fi
@@ -39,12 +39,16 @@ fi
 /bin/mount --make-shared /volume1
 echo "matrix-synology-boot-fix: /volume1 set to shared mount propagation"
 
-# Start any enabled matrix-*.service that is inactive (skipped at boot, not intentionally stopped)
-/bin/systemctl list-unit-files 'matrix-*.service' --state=enabled --no-legend 2>/dev/null | \
+# Start any enabled matrix-*.service that is inactive or failed.
+# Both states indicate the service did not come up at boot — either skipped by
+# Synology's boot ordering or failed due to Docker/mount-propagation not being
+# ready yet (the conditions above now satisfy those prerequisites).
+{{ devture_systemd_docker_base_host_command_systemctl }} list-unit-files 'matrix-*.service' --state=enabled --no-legend 2>/dev/null | \
     while read -r unit _state; do
         [ "$unit" = "matrix-synology-boot-fix.service" ] && continue
-        if [ "$(/bin/systemctl is-active "$unit" 2>/dev/null)" = "inactive" ]; then
-            echo "matrix-synology-boot-fix: starting $unit"
-            /bin/systemctl start "$unit"
+        status="$({{ devture_systemd_docker_base_host_command_systemctl }} is-active "$unit" 2>/dev/null)"
+        if [ "$status" = "inactive" ] || [ "$status" = "failed" ]; then
+            echo "matrix-synology-boot-fix: starting $unit (was $status)"
+            {{ devture_systemd_docker_base_host_command_systemctl }} start "$unit"
         fi
     done