diff --git a/common/modules/mixly-modules/common/statusbar-serial.js b/common/modules/mixly-modules/common/statusbar-serial.js
index d312917c..b5954df4 100644
--- a/common/modules/mixly-modules/common/statusbar-serial.js
+++ b/common/modules/mixly-modules/common/statusbar-serial.js
@@ -458,11 +458,13 @@ class StatusBarSerial extends PageBase {
 
     async open() {
         await this.#serial_.open(this.#config_.baud);
-        await this.#serial_.sleep(200);
-        try {
-            await this.#serial_.setDTRAndRTS(this.#config_.dtr, this.#config_.rts);
-        } catch (error) {
-            Debug.error(error);
+        if (goog.isElectron || Env.hasSocketServer) {
+            await this.#serial_.sleep(200);
+            try {
+                await this.#serial_.setDTRAndRTS(this.#config_.dtr, this.#config_.rts);
+            } catch (error) {
+                Debug.error(error);
+            }
         }
         if (SELECTED_BOARD?.serial?.ctrlCBtn) {
             await this.#serial_.sleep(500);
diff --git a/common/modules/mixly-modules/web/serialport.js b/common/modules/mixly-modules/web/serialport.js
index c8c0fcb2..f7d8328e 100644
--- a/common/modules/mixly-modules/web/serialport.js
+++ b/common/modules/mixly-modules/web/serialport.js
@@ -128,30 +128,23 @@ class WebSerialPort extends Serial {
     }
 
     async open(baud) {
-        return new Promise((resolve, reject) => {
-            const portsName = Serial.getCurrentPortsName();
-            const currentPortName = this.getPortName();
-            if (!portsName.includes(currentPortName)) {
-                reject('no device available');
-                return;
-            }
-            if (this.isOpened()) {
-                resolve();
-                return;
-            }
-            baud = baud ?? this.getBaudRate();
-            this.#serialport_ = WebSerialPort.getPort(currentPortName);
-            this.#serialport_.open({ baudRate: baud })
-                .then(() => {
-                    super.open(baud);
-                    super.setBaudRate(baud);
-                    this.#keepReading_ = true;
-                    this.onOpen();
-                    this.#addEventsListener_();
-                    resolve();
-                })
-                .catch(reject);
-        });
+        const portsName = Serial.getCurrentPortsName();
+        const currentPortName = this.getPortName();
+        if (!portsName.includes(currentPortName)) {
+            throw Error('no device available');
+            return;
+        }
+        if (this.isOpened()) {
+            return;
+        }
+        baud = baud ?? this.getBaudRate();
+        this.#serialport_ = WebSerialPort.getPort(currentPortName);
+        await this.#serialport_.open({ baudRate: baud });
+        super.open(baud);
+        super.setBaudRate(baud);
+        this.#keepReading_ = true;
+        this.onOpen();
+        this.#addEventsListener_();
     }
 
     async #waitForUnlock_(timeout) {
@@ -180,18 +173,13 @@ class WebSerialPort extends Serial {
     }
 
     async setBaudRate(baud) {
-        return new Promise((resolve, reject) => {
-            if (!this.isOpened()
-                || this.getBaudRate() === baud
-                || !this.baudRateIsLegal(baud)) {
-                resolve();
-                return;
-            }
-            this.close()
-                .then(() => this.open(baud))
-                .then(resolve)
-                .catch(reject);
-        });
+        if (!this.isOpened()
+            || this.getBaudRate() === baud
+            || !this.baudRateIsLegal(baud)) {
+            return;
+        }
+        await this.close();
+        await this.open(baud);
     }
 
     async sendString(str) {
@@ -215,21 +203,14 @@ class WebSerialPort extends Serial {
     }
 
     async setDTRAndRTS(dtr, rts) {
-        return new Promise((resolve, reject) => {
-            if (!this.isOpened()) {
-                resolve();
-                return;
-            }
-            this.#serialport_.setSignals({
-                dataTerminalReady: dtr,
-                requestToSend: rts
-            })
-            .then(() => {
-                super.setDTRAndRTS(dtr, rts);
-                resolve();
-            })
-            .catch(reject);
+        if (!this.isOpened()) {
+            return;
+        }
+        await this.#serialport_.setSignals({
+            dataTerminalReady: dtr,
+            requestToSend: rts
         });
+        super.setDTRAndRTS(dtr, rts);
     }
 
     async setDTR(dtr) {