diff --git a/cylc/uiserver/client.py b/cylc/uiserver/client.py
index a0837f1d..42bf77b7 100644
--- a/cylc/uiserver/client.py
+++ b/cylc/uiserver/client.py
@@ -66,8 +66,14 @@ async def async_request(
         if not args:
             args = {}
 
-        with open(API_INFO_FILE, "r") as api_file:
-            api_info = json.loads(api_file.read())
+        try:
+            with open(API_INFO_FILE, "r") as api_file:
+                api_info = json.loads(api_file.read())
+        except FileNotFoundError:
+            raise ClientError(
+                'API info not found, is the UI-Server running?\n'
+                f'({API_INFO_FILE})'
+            )
 
         # send message
         msg: Dict[str, Any] = {'command': command, 'args': args}
@@ -96,6 +102,11 @@ async def async_request(
                 request_timeout=float(self.timeout)
             )
             res = await AsyncHTTPClient().fetch(request)
+        except ConnectionRefusedError:
+            raise ClientError(
+                'Connection refused, is the UI-Server running?\n'
+                f'({api_info["url"]}cylc/graphql)'
+            )
         except HTTPClientError as exc:
             raise ClientError(
                 'Client error with Hub/UI-Server request.',
@@ -147,7 +158,7 @@ def get_header(self) -> dict:
                 'comms_method':
                     os.getenv(
                         "CLIENT_COMMS_METH",
-                        default=CommsMeth.HTTP.value
+                        default=CommsMeth.HTTPS.value
                     )
             }
         }
diff --git a/cylc/uiserver/resolvers.py b/cylc/uiserver/resolvers.py
index 4bc596e2..608ffc47 100644
--- a/cylc/uiserver/resolvers.py
+++ b/cylc/uiserver/resolvers.py
@@ -271,7 +271,7 @@ async def play(cls, workflows, args, workflows_mgr, log):
                 args.pop('cylc_version')
 
             # build the command
-            cmd = ['cylc', 'play', '--color=never']
+            cmd = ['cylc', 'play', '--color=never', '--comms-method=zmq']
             cmd = _build_cmd(cmd, args)
 
         except Exception as exc: