diff --git a/conf/nginx/server.tpl.conf b/conf/nginx/server.tpl.conf
index ecb9b7fb9..40f85b328 100644
--- a/conf/nginx/server.tpl.conf
+++ b/conf/nginx/server.tpl.conf
@@ -6,7 +6,7 @@ map $http_upgrade $connection_upgrade {
 server {
     listen 80;
     listen [::]:80;
-    server_name {{ domain }}{% if xmpp_enabled != "True" %} xmpp-upload.{{ domain }}{% endif %};
+    server_name {{ domain }}{% if xmpp_enabled != "True" %} xmpp-upload.{{ domain }} muc.{{ domain }}{% endif %};
 
     access_by_lua_file /usr/share/ssowat/access.lua;
 
diff --git a/locales/en.json b/locales/en.json
index 26cd3dd75..df444e898 100644
--- a/locales/en.json
+++ b/locales/en.json
@@ -311,6 +311,7 @@
     "disk_space_not_sufficient_install": "There is not enough disk space left to install this application",
     "disk_space_not_sufficient_update": "There is not enough disk space left to update this application",
     "domain_cannot_add_xmpp_upload": "You cannot add domains starting with 'xmpp-upload.'. This kind of name is reserved for the XMPP upload feature integrated into YunoHost.",
+    "domain_cannot_add_muc_upload": "You cannot add domains starting with 'muc.'. This kind of name is reserved for the XMPP multi-users chat feature integrated into YunoHost.",
     "domain_cannot_remove_main": "You cannot remove '{domain}' since it's the main domain, you first need to set another domain as the main domain using 'yunohost domain main-domain -n <another-domain>'; here is the list of candidate domains: {other_domains}",
     "domain_cannot_remove_main_add_new_one": "You cannot remove '{domain}' since it's the main domain and your only domain, you need to first add another domain using 'yunohost domain add <another-domain.com>', then set is as the main domain using 'yunohost domain main-domain -n <another-domain.com>' and then you can remove the domain '{domain}' using 'yunohost domain remove {domain}'.'",
     "domain_cert_gen_failed": "Could not generate certificate",
diff --git a/src/certificate.py b/src/certificate.py
index 04a33dbfd..852cdf6a7 100644
--- a/src/certificate.py
+++ b/src/certificate.py
@@ -568,9 +568,10 @@ def _prepare_certificate_signing_request(domain, key_file, output_folder):
     # Set the domain
     csr.get_subject().CN = domain
 
-    from yunohost.domain import domain_list, domain_config_get
+    from yunohost.domain import domain_config_get
 
-    # If XMPP is enabled for this domain, add xmpp-upload domain
+    # If XMPP is enabled for this domain, add xmpp-upload and muc subdomains
+    # in subject alternate names
     if domain_config_get(domain, key="feature.xmpp.xmpp") == 1:
         subdomain = "xmpp-upload." + domain
         xmpp_records = (
@@ -579,24 +580,30 @@ def _prepare_certificate_signing_request(domain, key_file, output_folder):
             ).get("data")
             or {}
         )
-        if xmpp_records.get("CNAME:xmpp-upload") == "OK":
+        sanlist = []
+        for sub in ('xmpp-upload', 'muc'):
+            subdomain = sub + "." + domain
+            if xmpp_records.get("CNAME:" + sub) == "OK":
+                sanlist.append(("DNS:" + subdomain))
+            else:
+                logger.warning(
+                    m18n.n(
+                        "certmanager_warning_subdomain_dns_record",
+                        subdomain=subdomain,
+                        domain=domain,
+                    )
+                )
+
+        if sanlist:
             csr.add_extensions(
                 [
                     crypto.X509Extension(
                         b"subjectAltName",
                         False,
-                        ("DNS:" + subdomain).encode("utf8"),
+                        (", ".join(sanlist)).encode("utf-8"),
                     )
                 ]
             )
-        else:
-            logger.warning(
-                m18n.n(
-                    "certmanager_warning_subdomain_dns_record",
-                    subdomain=subdomain,
-                    domain=domain,
-                )
-            )
 
     # Set the key
     with open(key_file, "rt") as f:
diff --git a/src/domain.py b/src/domain.py
index 489e48e16..45abf1006 100644
--- a/src/domain.py
+++ b/src/domain.py
@@ -229,6 +229,9 @@ def domain_add(operation_logger, domain, dyndns=False):
     if domain.startswith("xmpp-upload."):
         raise YunohostValidationError("domain_cannot_add_xmpp_upload")
 
+    if domain.startswith("muc."):
+        raise YunohostError("domain_cannot_add_muc_upload")
+
     ldap = _get_ldap_interface()
 
     try: