diff --git a/bindings/matrix-sdk-ffi/src/client.rs b/bindings/matrix-sdk-ffi/src/client.rs
index 0ddfbe29df7..7d71473a0d4 100644
--- a/bindings/matrix-sdk-ffi/src/client.rs
+++ b/bindings/matrix-sdk-ffi/src/client.rs
@@ -388,11 +388,13 @@ impl Client {
 
         self.restore_session_inner(auth_session).await?;
 
-        if let Some(sliding_sync_proxy) = sliding_sync_proxy {
-            let sliding_sync_proxy = Url::parse(&sliding_sync_proxy)
-                .map_err(|error| ClientError::Generic { msg: error.to_string() })?;
+        if !self.inner.is_simplified_sliding_sync_enabled() {
+            if let Some(sliding_sync_proxy) = sliding_sync_proxy {
+                let sliding_sync_proxy = Url::parse(&sliding_sync_proxy)
+                    .map_err(|error| ClientError::Generic { msg: error.to_string() })?;
 
-            self.inner.set_sliding_sync_proxy(Some(sliding_sync_proxy));
+                self.inner.set_sliding_sync_proxy(Some(sliding_sync_proxy));
+            }
         }
 
         Ok(())
diff --git a/bindings/matrix-sdk-ffi/src/client_builder.rs b/bindings/matrix-sdk-ffi/src/client_builder.rs
index a7cca427b28..b5db78cba4b 100644
--- a/bindings/matrix-sdk-ffi/src/client_builder.rs
+++ b/bindings/matrix-sdk-ffi/src/client_builder.rs
@@ -530,8 +530,10 @@ impl ClientBuilder {
         // `Some(_)` value in `builder.sliding_sync_proxy`. That's really important: It
         // might not break an existing app session, but it is likely to break a new
         // session, which not immediate to detect if there is no test.
-        if let Some(sliding_sync_proxy) = builder.sliding_sync_proxy {
-            sdk_client.set_sliding_sync_proxy(Some(Url::parse(&sliding_sync_proxy)?));
+        if !builder.is_simplified_sliding_sync_enabled {
+            if let Some(sliding_sync_proxy) = builder.sliding_sync_proxy {
+                sdk_client.set_sliding_sync_proxy(Some(Url::parse(&sliding_sync_proxy)?));
+            }
         }
 
         Ok(Arc::new(
diff --git a/crates/matrix-sdk/src/client/mod.rs b/crates/matrix-sdk/src/client/mod.rs
index afb1327f269..0fe65251d0c 100644
--- a/crates/matrix-sdk/src/client/mod.rs
+++ b/crates/matrix-sdk/src/client/mod.rs
@@ -482,7 +482,7 @@ impl Client {
 
     /// Check whether Simplified MSC3575 must be used.
     #[cfg(feature = "experimental-sliding-sync")]
-    pub(crate) fn is_simplified_sliding_sync_enabled(&self) -> bool {
+    pub fn is_simplified_sliding_sync_enabled(&self) -> bool {
         self.inner.is_simplified_sliding_sync_enabled
     }