diff --git a/backend/src/app.ts b/backend/src/app.ts
index 248c6aa..3cef0b1 100644
--- a/backend/src/app.ts
+++ b/backend/src/app.ts
@@ -76,7 +76,7 @@ const run = () => {
 
     // Load extra routes
     devtoken.routes( app, foss );
-    room.routes( app, foss );
+    room.routes( app, foss, config );
     user.routes( app, foss );
 
 
diff --git a/backend/src/manager/rooms/sse.ts b/backend/src/manager/rooms/sse.ts
index 0ebf976..a0cd99c 100644
--- a/backend/src/manager/rooms/sse.ts
+++ b/backend/src/manager/rooms/sse.ts
@@ -1,10 +1,13 @@
+import {
+    Config
+} from '../../dtype/config';
 import express from 'express';
 import {
     generateToken
 } from '../../token';
 import rooms from '.';
 
-export const sseMiddleware = ( kind: 'client' | 'trackingClient' ) => {
+export const sseMiddleware = ( kind: 'client' | 'trackingClient', config?: Config ) => {
     return ( request: express.Request, response: express.Response ) => {
         if ( typeof request.params.id !== 'string' )
             return response.sendStatus( 400 );
@@ -20,7 +23,11 @@ export const sseMiddleware = ( kind: 'client' | 'trackingClient' ) => {
         } );
         response.status( 200 );
         response.flushHeaders();
-        response.write( 'data: connected\n\n' );
+
+        if ( kind === 'trackingClient' || config?.clientMode === 'poll' )
+            response.write( 'data: use-poll\n\n' );
+        else
+            response.write( 'data: connected\n\n' );
 
         const token = generateToken( 20 );
 
diff --git a/backend/src/manager/users/ownership.ts b/backend/src/manager/users/ownership.ts
index f637cae..d264f5f 100644
--- a/backend/src/manager/users/ownership.ts
+++ b/backend/src/manager/users/ownership.ts
@@ -4,7 +4,9 @@ import {
 } from '../../sdk';
 import express from 'express';
 
-const cache = {};
+const cache: {
+    [key: string]: boolean
+} = {};
 
 export const getOwnershipManager = ( foss: boolean ) => {
     const storeSdk = getStoreSdk( foss );
diff --git a/backend/src/routes/room/index.ts b/backend/src/routes/room/index.ts
index c9d563b..3315fac 100644
--- a/backend/src/routes/room/index.ts
+++ b/backend/src/routes/room/index.ts
@@ -1,3 +1,6 @@
+import {
+    Config
+} from '../../dtype/config';
 import express from 'express';
 import {
     getLoginSdk
@@ -9,12 +12,12 @@ import rooms from '../../manager/rooms';
 import tracking from './tracking';
 import update from './update';
 
-const routes = ( app: express.Application, foss: boolean ) => {
+const routes = ( app: express.Application, foss: boolean, config: Config ) => {
     const sdk = getLoginSdk( foss );
     const ownership = getOwnershipManager( foss );
 
     tracking.routes( app, foss );
-    update.routes( app, foss );
+    update.routes( app, foss, config );
 
     app.get(
         '/room/create',
diff --git a/backend/src/routes/room/update.ts b/backend/src/routes/room/update.ts
index dee602c..d38ff27 100644
--- a/backend/src/routes/room/update.ts
+++ b/backend/src/routes/room/update.ts
@@ -1,3 +1,6 @@
+import {
+    Config
+} from '../../dtype/config';
 import bodyParser from 'body-parser';
 import corsManager from '../../corsManager';
 import express from 'express';
@@ -10,11 +13,11 @@ import {
     sseMiddleware
 } from '../../manager/rooms/sse';
 
-const routes = ( app: express.Application, foss: boolean ) => {
+const routes = ( app: express.Application, foss: boolean, config: Config ) => {
     const sdk = getLoginSdk( foss );
 
     // FIXME: Here, if not in sse mode, simply close the connection after sending 'poll'
-    app.get( '/room/:id/connect', corsManager.middleware( false ), sseMiddleware( 'client' ) );
+    app.get( '/room/:id/connect', corsManager.middleware( false ), sseMiddleware( 'client', config ) );
 
     app.get( '/room/:id/poll', corsManager.middleware( false ), ( request: express.Request, response: express.Response ) => {
         if ( typeof request.params.id !== 'string' )