diff --git a/roles/matrix-synapse/defaults/main.yml b/roles/matrix-synapse/defaults/main.yml
index df0b1889a..1564b8437 100644
--- a/roles/matrix-synapse/defaults/main.yml
+++ b/roles/matrix-synapse/defaults/main.yml
@@ -3,7 +3,7 @@
 
 matrix_synapse_enabled: true
 
-matrix_synapse_docker_image: "matrixdotorg/synapse:v1.10.1"
+matrix_synapse_docker_image: "matrixdotorg/synapse:v1.11.0"
 matrix_synapse_docker_image_force_pull: "{{ matrix_synapse_docker_image.endswith(':latest') }}"
 
 matrix_synapse_base_path: "{{ matrix_base_data_path }}/synapse"
diff --git a/roles/matrix-synapse/templates/synapse/homeserver.yaml.j2 b/roles/matrix-synapse/templates/synapse/homeserver.yaml.j2
index 803eb222e..49a9a9063 100644
--- a/roles/matrix-synapse/templates/synapse/homeserver.yaml.j2
+++ b/roles/matrix-synapse/templates/synapse/homeserver.yaml.j2
@@ -1,5 +1,11 @@
 #jinja2: lstrip_blocks: "True"
-# vim:ft=yaml
+# Configuration file for Synapse.
+#
+# This is a YAML file: see [1] for a quick introduction. Note in particular
+# that *indentation is important*: all the elements of a list or dictionary
+# should have the same indentation.
+#
+# [1] https://docs.ansible.com/ansible/latest/reference_appendices/YAMLSyntax.html
 
 ## Server ##
 
@@ -471,6 +477,11 @@ tls_private_key_path: {{ matrix_synapse_tls_private_key_path|to_json }}
 # ACME support: This will configure Synapse to request a valid TLS certificate
 # for your configured `server_name` via Let's Encrypt.
 #
+# Note that ACME v1 is now deprecated, and Synapse currently doesn't support
+# ACME v2. This means that this feature currently won't work with installs set
+# up after November 2019. For more info, and alternative solutions, see
+# https://github.com/matrix-org/synapse/blob/master/docs/ACME.md#deprecation-of-acme-v1
+#
 # Note that provisioning a certificate in this way requires port 80 to be
 # routed to Synapse so that it can complete the http-01 ACME challenge.
 # By default, if you enable ACME support, Synapse will attempt to listen on
@@ -1817,3 +1828,6 @@ opentracing:
     #
     #  logging:
     #    false
+
+
+# vim:ft=yaml