diff --git a/app/src/main/java/nodomain/freeyourgadget/gadgetbridge/devices/moyoung/AbstractMoyoungDeviceCoordinator.java b/app/src/main/java/nodomain/freeyourgadget/gadgetbridge/devices/moyoung/AbstractMoyoungDeviceCoordinator.java
index 7cc59abc2..6fe272d6e 100644
--- a/app/src/main/java/nodomain/freeyourgadget/gadgetbridge/devices/moyoung/AbstractMoyoungDeviceCoordinator.java
+++ b/app/src/main/java/nodomain/freeyourgadget/gadgetbridge/devices/moyoung/AbstractMoyoungDeviceCoordinator.java
@@ -208,4 +208,8 @@ public abstract class AbstractMoyoungDeviceCoordinator extends AbstractDeviceCoo
     public MoyoungSetting[] getSupportedSettings() {
         return MOYOUNG_SETTINGS;
     }
+
+    public int getMtu() {
+        return 20;
+    }
 }
diff --git a/app/src/main/java/nodomain/freeyourgadget/gadgetbridge/devices/moyoung/ColmiI28UltraCoordinator.java b/app/src/main/java/nodomain/freeyourgadget/gadgetbridge/devices/moyoung/ColmiI28UltraCoordinator.java
index 578d58063..3b9cb7778 100644
--- a/app/src/main/java/nodomain/freeyourgadget/gadgetbridge/devices/moyoung/ColmiI28UltraCoordinator.java
+++ b/app/src/main/java/nodomain/freeyourgadget/gadgetbridge/devices/moyoung/ColmiI28UltraCoordinator.java
@@ -55,4 +55,9 @@ public class ColmiI28UltraCoordinator extends AbstractMoyoungDeviceCoordinator {
     public String getManufacturer() {
         return "Colmi";
     }
+
+    @Override
+    public int getMtu() {
+        return 508;
+    }
 }
\ No newline at end of file
diff --git a/app/src/main/java/nodomain/freeyourgadget/gadgetbridge/service/devices/moyoung/FetchDataOperation.java b/app/src/main/java/nodomain/freeyourgadget/gadgetbridge/service/devices/moyoung/FetchDataOperation.java
index bf0df61c5..b5216fe30 100644
--- a/app/src/main/java/nodomain/freeyourgadget/gadgetbridge/service/devices/moyoung/FetchDataOperation.java
+++ b/app/src/main/java/nodomain/freeyourgadget/gadgetbridge/service/devices/moyoung/FetchDataOperation.java
@@ -57,13 +57,13 @@ public class FetchDataOperation extends AbstractBTLEOperation<MoyoungDeviceSuppo
     @Override
     protected void doPerform() throws IOException {
         TransactionBuilder builder = performInitialized("FetchDataOperation");
-        getSupport().sendPacket(builder, MoyoungPacketOut.buildPacket(MoyoungConstants.CMD_SYNC_PAST_SLEEP_AND_STEP, new byte[] { MoyoungConstants.ARG_SYNC_YESTERDAY_SLEEP }));
-        getSupport().sendPacket(builder, MoyoungPacketOut.buildPacket(MoyoungConstants.CMD_SYNC_PAST_SLEEP_AND_STEP, new byte[] { MoyoungConstants.ARG_SYNC_DAY_BEFORE_YESTERDAY_SLEEP }));
-        getSupport().sendPacket(builder, MoyoungPacketOut.buildPacket(MoyoungConstants.CMD_SYNC_SLEEP, new byte[0]));
-        getSupport().sendPacket(builder, MoyoungPacketOut.buildPacket(MoyoungConstants.CMD_SYNC_PAST_SLEEP_AND_STEP, new byte[] { MoyoungConstants.ARG_SYNC_YESTERDAY_STEPS }));
-        getSupport().sendPacket(builder, MoyoungPacketOut.buildPacket(MoyoungConstants.CMD_SYNC_PAST_SLEEP_AND_STEP, new byte[] { MoyoungConstants.ARG_SYNC_DAY_BEFORE_YESTERDAY_STEPS }));
+        getSupport().sendPacket(builder, MoyoungPacketOut.buildPacket(getSupport().getMtu(), MoyoungConstants.CMD_SYNC_PAST_SLEEP_AND_STEP, new byte[] { MoyoungConstants.ARG_SYNC_YESTERDAY_SLEEP }));
+        getSupport().sendPacket(builder, MoyoungPacketOut.buildPacket(getSupport().getMtu(), MoyoungConstants.CMD_SYNC_PAST_SLEEP_AND_STEP, new byte[] { MoyoungConstants.ARG_SYNC_DAY_BEFORE_YESTERDAY_SLEEP }));
+        getSupport().sendPacket(builder, MoyoungPacketOut.buildPacket(getSupport().getMtu(), MoyoungConstants.CMD_SYNC_SLEEP, new byte[0]));
+        getSupport().sendPacket(builder, MoyoungPacketOut.buildPacket(getSupport().getMtu(), MoyoungConstants.CMD_SYNC_PAST_SLEEP_AND_STEP, new byte[] { MoyoungConstants.ARG_SYNC_YESTERDAY_STEPS }));
+        getSupport().sendPacket(builder, MoyoungPacketOut.buildPacket(getSupport().getMtu(), MoyoungConstants.CMD_SYNC_PAST_SLEEP_AND_STEP, new byte[] { MoyoungConstants.ARG_SYNC_DAY_BEFORE_YESTERDAY_STEPS }));
         builder.read(getCharacteristic(MoyoungConstants.UUID_CHARACTERISTIC_STEPS));
-        getSupport().sendPacket(builder, MoyoungPacketOut.buildPacket(MoyoungConstants.CMD_QUERY_MOVEMENT_HEART_RATE, new byte[] { }));
+        getSupport().sendPacket(builder, MoyoungPacketOut.buildPacket(getSupport().getMtu(), MoyoungConstants.CMD_QUERY_MOVEMENT_HEART_RATE, new byte[] { }));
         builder.queue(getQueue());
 
         updateProgressAndCheckFinish();
diff --git a/app/src/main/java/nodomain/freeyourgadget/gadgetbridge/service/devices/moyoung/MoyoungDeviceSupport.java b/app/src/main/java/nodomain/freeyourgadget/gadgetbridge/service/devices/moyoung/MoyoungDeviceSupport.java
index 69f72f247..85e687de4 100644
--- a/app/src/main/java/nodomain/freeyourgadget/gadgetbridge/service/devices/moyoung/MoyoungDeviceSupport.java
+++ b/app/src/main/java/nodomain/freeyourgadget/gadgetbridge/service/devices/moyoung/MoyoungDeviceSupport.java
@@ -130,11 +130,15 @@ public class MoyoungDeviceSupport extends AbstractBTLEDeviceSupport {
 
     private Handler idleUpdateHandler = new Handler();
 
-    public static final int MTU = 20; // TODO: there seems to be some way to change this value...?
+    private int mtu = 20;
     private MoyoungPacketIn packetIn = new MoyoungPacketIn();
 
     private boolean realTimeHeartRate;
 
+    public int getMtu() {
+        return this.mtu;
+    }
+
     public MoyoungDeviceSupport() {
         super(LOG);
         batteryCmd.level = ActivitySample.NOT_MEASURED;
@@ -159,6 +163,8 @@ public class MoyoungDeviceSupport extends AbstractBTLEDeviceSupport {
 
     @Override
     protected TransactionBuilder initializeDevice(TransactionBuilder builder) {
+        mtu = ((AbstractMoyoungDeviceCoordinator) getDevice().getDeviceCoordinator()).getMtu();
+
         builder.add(new SetDeviceStateAction(getDevice(), GBDevice.State.INITIALIZING, getContext()));
         builder.notify(getCharacteristic(MoyoungConstants.UUID_CHARACTERISTIC_DATA_IN), true);
         deviceInfoProfile.requestDeviceInfo(builder);
@@ -172,7 +178,7 @@ public class MoyoungDeviceSupport extends AbstractBTLEDeviceSupport {
         builder.add(new SetDeviceStateAction(getDevice(), GBDevice.State.INITIALIZED, getContext()));
 
         // TODO: I would prefer this to be done when the alarms screen is open, not on initialization...
-        sendPacket(builder, MoyoungPacketOut.buildPacket(MoyoungConstants.CMD_QUERY_ALARM_CLOCK, new byte[0]));
+        sendPacket(builder, MoyoungPacketOut.buildPacket(mtu, MoyoungConstants.CMD_QUERY_ALARM_CLOCK, new byte[0]));
 
         return builder;
     }
@@ -197,7 +203,7 @@ public class MoyoungDeviceSupport extends AbstractBTLEDeviceSupport {
     {
         MoyoungPacketOut packetOut = new MoyoungPacketOut(packet);
 
-        byte[] fragment = new byte[MTU];
+        byte[] fragment = new byte[Math.min(packet.length, mtu)];
         while(packetOut.getFragment(fragment))
         {
             builder.write(getTargetCharacteristicForPacketType(packet[4]), fragment.clone());
@@ -485,7 +491,7 @@ public class MoyoungDeviceSupport extends AbstractBTLEDeviceSupport {
             byte[] payload = new byte[str.length + 1];
             payload[0] = type;
             System.arraycopy(str, 0, payload, 1, str.length);
-            sendPacket(builder, MoyoungPacketOut.buildPacket(MoyoungConstants.CMD_SEND_MESSAGE, payload));
+            sendPacket(builder, MoyoungPacketOut.buildPacket(mtu, MoyoungConstants.CMD_SEND_MESSAGE, payload));
             builder.queue(getQueue());
         } catch (IOException e) {
             LOG.error("Error sending notification: ", e);
@@ -518,7 +524,7 @@ public class MoyoungDeviceSupport extends AbstractBTLEDeviceSupport {
         ByteBuffer buffer = ByteBuffer.allocate(5);
         buffer.putInt(MoyoungConstants.LocalTimeToWatchTime(new Date())); // The watch is hardcoded to GMT+8 internally...
         buffer.put((byte)8); // I guess this means GMT+8 but changing it has no effect at all (it was hardcoded in the original app too)
-        sendPacket(builder, MoyoungPacketOut.buildPacket(MoyoungConstants.CMD_SYNC_TIME, buffer.array()));
+        sendPacket(builder, MoyoungPacketOut.buildPacket(mtu, MoyoungConstants.CMD_SYNC_TIME, buffer.array()));
     }
 
     @Override
@@ -615,7 +621,7 @@ public class MoyoungDeviceSupport extends AbstractBTLEDeviceSupport {
                 else
                     repeat = 2;
                 buffer.put(repeat);
-                sendPacket(builder, MoyoungPacketOut.buildPacket(MoyoungConstants.CMD_SET_ALARM_CLOCK, buffer.array()));
+                sendPacket(builder, MoyoungPacketOut.buildPacket(mtu, MoyoungConstants.CMD_SET_ALARM_CLOCK, buffer.array()));
             }
             builder.queue(getQueue());
         } catch (IOException e) {
@@ -1034,7 +1040,7 @@ public class MoyoungDeviceSupport extends AbstractBTLEDeviceSupport {
 
         try {
             TransactionBuilder builder = performInitialized("shutdown");
-            sendPacket(builder, MoyoungPacketOut.buildPacket(MoyoungConstants.CMD_SHUTDOWN, new byte[] { -1 }));
+            sendPacket(builder, MoyoungPacketOut.buildPacket(mtu, MoyoungConstants.CMD_SHUTDOWN, new byte[] { -1 }));
             builder.queue(getQueue());
         } catch (IOException e) {
             LOG.error("Error sending reset command: ", e);
@@ -1045,7 +1051,7 @@ public class MoyoungDeviceSupport extends AbstractBTLEDeviceSupport {
     {
         try {
             TransactionBuilder builder = performInitialized("onHeartRateTest");
-            sendPacket(builder, MoyoungPacketOut.buildPacket(MoyoungConstants.CMD_TRIGGER_MEASURE_HEARTRATE, new byte[] { start ? (byte)0 : (byte)-1 }));
+            sendPacket(builder, MoyoungPacketOut.buildPacket(mtu, MoyoungConstants.CMD_TRIGGER_MEASURE_HEARTRATE, new byte[] { start ? (byte)0 : (byte)-1 }));
             builder.queue(getQueue());
         } catch (IOException e) {
             LOG.error("Error sending heart rate test command: ", e);
@@ -1085,7 +1091,7 @@ public class MoyoungDeviceSupport extends AbstractBTLEDeviceSupport {
         {
             try {
                 TransactionBuilder builder = performInitialized("onFindDevice");
-                sendPacket(builder, MoyoungPacketOut.buildPacket(MoyoungConstants.CMD_FIND_MY_WATCH, new byte[0]));
+                sendPacket(builder, MoyoungPacketOut.buildPacket(mtu, MoyoungConstants.CMD_FIND_MY_WATCH, new byte[0]));
                 builder.queue(getQueue());
             } catch (IOException e) {
                 LOG.error("Error while finding device: ", e);
@@ -1123,7 +1129,7 @@ public class MoyoungDeviceSupport extends AbstractBTLEDeviceSupport {
 
     private <T> void sendSetting(TransactionBuilder builder, MoyoungSetting<T> setting, T newValue)
     {
-        sendPacket(builder, MoyoungPacketOut.buildPacket(setting.cmdSet, setting.encode(newValue)));
+        sendPacket(builder, MoyoungPacketOut.buildPacket(mtu, setting.cmdSet, setting.encode(newValue)));
     }
 
     private <T> void sendSetting(MoyoungSetting<T> setting, T newValue)
@@ -1146,7 +1152,7 @@ public class MoyoungDeviceSupport extends AbstractBTLEDeviceSupport {
 
         try {
             TransactionBuilder builder = performInitialized("querySetting");
-            sendPacket(builder, MoyoungPacketOut.buildPacket(setting.cmdQuery, new byte[0]));
+            sendPacket(builder, MoyoungPacketOut.buildPacket(mtu, setting.cmdQuery, new byte[0]));
             builder.queue(getQueue());
             queriedSettings.add(setting);
         } catch (IOException e) {
@@ -1485,10 +1491,10 @@ public class MoyoungDeviceSupport extends AbstractBTLEDeviceSupport {
                 packetWeatherToday.putShort(weatherToday.pm25);
             packetWeatherToday.put(weatherToday.lunar_or_festival.getBytes("unicodebigunmarked"));
             packetWeatherToday.put(weatherToday.city.getBytes("unicodebigunmarked"));
-            sendPacket(builder, MoyoungPacketOut.buildPacket(MoyoungConstants.CMD_SET_WEATHER_TODAY, packetWeatherToday.array()));
+            sendPacket(builder, MoyoungPacketOut.buildPacket(mtu, MoyoungConstants.CMD_SET_WEATHER_TODAY, packetWeatherToday.array()));
 
-            ByteBuffer packetWeatherForecast = ByteBuffer.allocate(6 * 3);
-            for(int i = 0; i < 6; i++)
+            ByteBuffer packetWeatherForecast = ByteBuffer.allocate(7 * 3);
+            for(int i = 0; i < 7; i++)
             {
                 MoyoungWeatherForecast forecast;
                 if (weatherSpec.forecasts.size() > i)
@@ -1499,7 +1505,7 @@ public class MoyoungDeviceSupport extends AbstractBTLEDeviceSupport {
                 packetWeatherForecast.put(forecast.minTemp);
                 packetWeatherForecast.put(forecast.maxTemp);
             }
-            sendPacket(builder, MoyoungPacketOut.buildPacket(MoyoungConstants.CMD_SET_WEATHER_FUTURE, packetWeatherForecast.array()));
+            sendPacket(builder, MoyoungPacketOut.buildPacket(mtu, MoyoungConstants.CMD_SET_WEATHER_FUTURE, packetWeatherForecast.array()));
 
             builder.queue(getQueue());
         } catch (IOException e) {
diff --git a/app/src/main/java/nodomain/freeyourgadget/gadgetbridge/service/devices/moyoung/MoyoungPacketOut.java b/app/src/main/java/nodomain/freeyourgadget/gadgetbridge/service/devices/moyoung/MoyoungPacketOut.java
index 18efef729..b570cbb7c 100644
--- a/app/src/main/java/nodomain/freeyourgadget/gadgetbridge/service/devices/moyoung/MoyoungPacketOut.java
+++ b/app/src/main/java/nodomain/freeyourgadget/gadgetbridge/service/devices/moyoung/MoyoungPacketOut.java
@@ -59,12 +59,12 @@ public class MoyoungPacketOut extends MoyoungPacket {
      * @param payload The packet payload
      * @return The encoded packet
      */
-    public static byte[] buildPacket(byte packetType, @NonNull byte[] payload)
+    public static byte[] buildPacket(int mtu, byte packetType, @NonNull byte[] payload)
     {
         byte[] packet = new byte[payload.length + 5];
         packet[0] = (byte)0xFE;
         packet[1] = (byte)0xEA;
-        if (MoyoungDeviceSupport.MTU == 20)
+        if (mtu == 20)
         {
             packet[2] = 16;
             packet[3] = (byte)(packet.length & 0xFF);
diff --git a/app/src/main/java/nodomain/freeyourgadget/gadgetbridge/service/devices/moyoung/QuerySettingsOperation.java b/app/src/main/java/nodomain/freeyourgadget/gadgetbridge/service/devices/moyoung/QuerySettingsOperation.java
index 02d15e868..ea670d448 100644
--- a/app/src/main/java/nodomain/freeyourgadget/gadgetbridge/service/devices/moyoung/QuerySettingsOperation.java
+++ b/app/src/main/java/nodomain/freeyourgadget/gadgetbridge/service/devices/moyoung/QuerySettingsOperation.java
@@ -68,7 +68,7 @@ public class QuerySettingsOperation extends AbstractBTLEOperation<MoyoungDeviceS
             if (setting.cmdQuery == -1)
                 continue;
 
-            getSupport().sendPacket(builder, MoyoungPacketOut.buildPacket(setting.cmdQuery, new byte[0]));
+            getSupport().sendPacket(builder, MoyoungPacketOut.buildPacket(getSupport().getMtu(), setting.cmdQuery, new byte[0]));
         }
         builder.queue(getQueue());
     }
diff --git a/app/src/main/java/nodomain/freeyourgadget/gadgetbridge/service/devices/moyoung/TrainingFinishedDataOperation.java b/app/src/main/java/nodomain/freeyourgadget/gadgetbridge/service/devices/moyoung/TrainingFinishedDataOperation.java
index 75a82f832..b10a8b769 100644
--- a/app/src/main/java/nodomain/freeyourgadget/gadgetbridge/service/devices/moyoung/TrainingFinishedDataOperation.java
+++ b/app/src/main/java/nodomain/freeyourgadget/gadgetbridge/service/devices/moyoung/TrainingFinishedDataOperation.java
@@ -136,7 +136,7 @@ public class TrainingFinishedDataOperation extends AbstractBTLEOperation<Moyoung
     private void queryMoreData() {
         try {
             TransactionBuilder builder = performInitialized("TrainingFinishedDataOperation");
-            getSupport().sendPacket(builder, MoyoungPacketOut.buildPacket(MoyoungConstants.CMD_QUERY_LAST_DYNAMIC_RATE, new byte[0]));
+            getSupport().sendPacket(builder, MoyoungPacketOut.buildPacket(getSupport().getMtu(), MoyoungConstants.CMD_QUERY_LAST_DYNAMIC_RATE, new byte[0]));
             builder.queue(getQueue());
         } catch (IOException e) {
             LOG.error("Error fetching training data: ", e);
@@ -192,7 +192,7 @@ public class TrainingFinishedDataOperation extends AbstractBTLEOperation<Moyoung
 
         try {
             TransactionBuilder builder = performInitialized("TrainingFinishedDataOperation fetch training type");
-            getSupport().sendPacket(builder, MoyoungPacketOut.buildPacket(MoyoungConstants.CMD_QUERY_MOVEMENT_HEART_RATE, new byte[] { }));
+            getSupport().sendPacket(builder, MoyoungPacketOut.buildPacket(getSupport().getMtu(), MoyoungConstants.CMD_QUERY_MOVEMENT_HEART_RATE, new byte[] { }));
             builder.queue(getQueue());
         } catch (IOException e) {
             LOG.error("Error fetching training data: ", e);