diff --git a/src/gateway/server/ws-connection.ts b/src/gateway/server/ws-connection.ts
index 0a2dfaa212e..95a0bf9ffa3 100644
--- a/src/gateway/server/ws-connection.ts
+++ b/src/gateway/server/ws-connection.ts
@@ -267,16 +267,7 @@ export function attachGatewayWsConnectionHandler(params: AttachGatewayWsConnecti
       payload: { nonce: connectNonce, ts: Date.now() },
     });
 
-    const pingTimer = setInterval(() => {
-      if (!client) {
-        return;
-      }
-      try {
-        socket.ping();
-      } catch {
-        // close() clears the timer; ping can race with a socket already entering CLOSING.
-      }
-    }, 25_000);
+    let pingTimer: ReturnType<typeof setInterval> | undefined;
 
     const close = (code = 1000, reason?: string) => {
       if (closed) {
@@ -284,7 +275,9 @@ export function attachGatewayWsConnectionHandler(params: AttachGatewayWsConnecti
       }
       closed = true;
       clearTimeout(handshakeTimer);
-      clearInterval(pingTimer);
+      if (pingTimer !== undefined) {
+        clearInterval(pingTimer);
+      }
       releasePreauthBudget();
       if (client) {
         clients.delete(client);
@@ -435,6 +428,13 @@ export function attachGatewayWsConnectionHandler(params: AttachGatewayWsConnecti
         releasePreauthBudget();
         client = next;
         clients.add(next);
+        pingTimer = setInterval(() => {
+          try {
+            socket.ping();
+          } catch {
+            // close() clears the timer; ping can race with a socket already entering CLOSING.
+          }
+        }, 25_000);
         return true;
       },
       setHandshakeState: (next) => {