diff --git a/group_vars/matrix_servers b/group_vars/matrix_servers
index 508ea8a92..b3cffe8a7 100755
--- a/group_vars/matrix_servers
+++ b/group_vars/matrix_servers
@@ -4382,6 +4382,8 @@ matrix_sliding_sync_path_prefix: /sliding-sync
 
 matrix_sliding_sync_container_image_self_build: "{{ matrix_architecture not in ['amd64', 'arm64'] }}"
 
+matrix_sliding_sync_container_network: "{{ matrix_homeserver_container_network }}"
+
 matrix_sliding_sync_container_additional_networks: |
   {{
     (
@@ -4405,6 +4407,7 @@ matrix_sliding_sync_systemd_required_services_list_auto: |
     ([devture_postgres_identifier ~ '.service'] if (devture_postgres_enabled and matrix_sliding_sync_database_hostname == devture_postgres_connection_hostname) else [])
   }}
 
+matrix_sliding_sync_environment_variable_syncv3_server: "{{ matrix_homeserver_container_url }}"
 matrix_sliding_sync_environment_variable_syncv3_secret: "{{ '%s' | format(matrix_homeserver_generic_secret_key) | password_hash('sha512', 'ss.secret', rounds=655555) | to_uuid }}"
 
 matrix_sliding_sync_database_hostname: "{{ devture_postgres_connection_hostname if devture_postgres_enabled else '' }}"
diff --git a/roles/custom/matrix-sliding-sync/defaults/main.yml b/roles/custom/matrix-sliding-sync/defaults/main.yml
index 541070837..b2966f9cf 100644
--- a/roles/custom/matrix-sliding-sync/defaults/main.yml
+++ b/roles/custom/matrix-sliding-sync/defaults/main.yml
@@ -31,7 +31,7 @@ matrix_sliding_sync_container_image_force_pull: "{{ matrix_sliding_sync_containe
 matrix_sliding_sync_container_image_registry_prefix: ghcr.io/
 
 # The base container network. It will be auto-created by this role if it doesn't exist already.
-matrix_sliding_sync_container_network: matrix-sliding-sync
+matrix_sliding_sync_container_network: ''
 
 # A list of additional container networks that the container would be connected to.
 # The role does not create these networks, so make sure they already exist.
@@ -81,7 +81,7 @@ matrix_sliding_sync_systemd_required_services_list_custom: []
 matrix_sliding_sync_systemd_wanted_services_list: []
 
 # Controls the SYNCV3_SERVER environment variable
-matrix_sliding_sync_environment_variable_syncv3_server: "{{ matrix_homeserver_container_url }}"
+matrix_sliding_sync_environment_variable_syncv3_server: ""
 
 # Controls the SYNCV3_SECRET environment variable
 matrix_sliding_sync_environment_variable_syncv3_secret: ''
diff --git a/roles/custom/matrix-sliding-sync/tasks/validate_config.yml b/roles/custom/matrix-sliding-sync/tasks/validate_config.yml
index 5d36403ce..08a6e409a 100644
--- a/roles/custom/matrix-sliding-sync/tasks/validate_config.yml
+++ b/roles/custom/matrix-sliding-sync/tasks/validate_config.yml
@@ -8,4 +8,6 @@
     - matrix_sliding_sync_hostname
     - matrix_sliding_sync_path_prefix
     - matrix_sliding_sync_database_hostname
+    - matrix_sliding_sync_environment_variable_syncv3_server
     - matrix_sliding_sync_environment_variable_syncv3_secret
+    - matrix_sliding_sync_container_network