diff --git a/mobile/src/main/java/be/mygod/vpnhotspot/manage/RepeaterManager.kt b/mobile/src/main/java/be/mygod/vpnhotspot/manage/RepeaterManager.kt
index 796c8282..37522bf6 100644
--- a/mobile/src/main/java/be/mygod/vpnhotspot/manage/RepeaterManager.kt
+++ b/mobile/src/main/java/be/mygod/vpnhotspot/manage/RepeaterManager.kt
@@ -226,7 +226,7 @@ class RepeaterManager(private val parent: TetheringFragment) : Manager(), Servic
         return null
     }
     private suspend fun updateConfiguration(config: SoftApConfigurationCompat) {
-        val (band, channel) = config.requireSingleBand()
+        val (band, channel) = SoftApConfigurationCompat.requireSingleBand(config.channels)
         if (RepeaterService.safeMode) {
             RepeaterService.networkName = config.ssid
             RepeaterService.deviceAddress = config.bssid
diff --git a/mobile/src/main/java/be/mygod/vpnhotspot/net/wifi/SoftApConfigurationCompat.kt b/mobile/src/main/java/be/mygod/vpnhotspot/net/wifi/SoftApConfigurationCompat.kt
index fc4ee751..d9ba375e 100644
--- a/mobile/src/main/java/be/mygod/vpnhotspot/net/wifi/SoftApConfigurationCompat.kt
+++ b/mobile/src/main/java/be/mygod/vpnhotspot/net/wifi/SoftApConfigurationCompat.kt
@@ -333,6 +333,33 @@ data class SoftApConfigurationCompat(
             Build.VERSION.SDK_INT < 31 || isUserConfiguration(this) as Boolean,
             this,
         )
+
+        /**
+         * Only single band/channel can be supplied on API 23-30
+         */
+        fun requireSingleBand(channels: SparseIntArray): Pair<Int, Int> {
+            require(channels.size() == 1) { "Unsupported number of bands configured" }
+            return channels.keyAt(0) to channels.valueAt(0)
+        }
+        fun optimizeChannels(channels: SparseIntArray) = SparseIntArray(channels.size()).apply {
+            var setBand = 0
+            repeat(channels.size()) { i -> if (channels.valueAt(i) == 0) setBand = setBand or channels.keyAt(i) }
+            if (setBand != 0) append(setBand, 0)    // merge all bands into one
+            repeat(channels.size()) { i ->
+                val band = channels.keyAt(i)
+                if (band and setBand == 0) put(band, channels.valueAt(i))
+            }
+        }
+
+        @RequiresApi(30)
+        private fun setChannelsCompat(builder: Any, channels: SparseIntArray) = if (Build.VERSION.SDK_INT < 31) {
+            val (band, channel) = requireSingleBand(channels)
+            if (channel == 0) setBand(builder, band) else setChannel(builder, channel, band)
+        } else setChannels(builder, channels)
+        @get:RequiresApi(30)
+        private val staticBuilder by lazy { classBuilder.newInstance() }
+        @RequiresApi(30)
+        fun testPlatformValidity(channels: SparseIntArray) = setChannels(staticBuilder, channels)
     }
 
     @Suppress("DEPRECATION")
@@ -342,13 +369,6 @@ data class SoftApConfigurationCompat(
             bssidAddr = value?.addr
         }
 
-    /**
-     * Only single band/channel can be supplied on API 23-30
-     */
-    fun requireSingleBand(): Pair<Int, Int> {
-        require(channels.size() == 1) { "Unsupported number of bands configured" }
-        return channels.keyAt(0) to channels.valueAt(0)
-    }
     fun getChannel(band: Int): Int {
         var result = -1
         repeat(channels.size()) { i ->
@@ -367,17 +387,6 @@ data class SoftApConfigurationCompat(
             }, channel)
         }
     }
-    fun optimizeChannels(channels: SparseIntArray = this.channels) {
-        this.channels = SparseIntArray(channels.size()).apply {
-            var setBand = 0
-            repeat(channels.size()) { i -> if (channels.valueAt(i) == 0) setBand = setBand or channels.keyAt(i) }
-            if (setBand != 0) append(setBand, 0)    // merge all bands into one
-            repeat(channels.size()) { i ->
-                val band = channels.keyAt(i)
-                if (band and setBand == 0) put(band, channels.valueAt(i))
-            }
-        }
-    }
 
     fun setMacRandomizationEnabled(enabled: Boolean) {
         macRandomizationSetting = if (enabled) RANDOMIZATION_PERSISTENT else RANDOMIZATION_NONE
@@ -393,7 +402,7 @@ data class SoftApConfigurationCompat(
     @Deprecated("Class deprecated in framework, use toPlatform().toWifiConfiguration()")
     @Suppress("DEPRECATION")
     fun toWifiConfiguration(): android.net.wifi.WifiConfiguration {
-        val (band, channel) = requireSingleBand()
+        val (band, channel) = requireSingleBand(channels)
         val wc = underlying as? android.net.wifi.WifiConfiguration
         val result = if (wc == null) android.net.wifi.WifiConfiguration() else android.net.wifi.WifiConfiguration(wc)
         val original = wc?.toCompat()
@@ -437,11 +446,8 @@ data class SoftApConfigurationCompat(
         val builder = if (sac == null) classBuilder.newInstance() else newBuilder.newInstance(sac)
         setSsid(builder, ssid)
         setPassphrase(builder, if (securityType == SoftApConfiguration.SECURITY_TYPE_OPEN) null else passphrase,
-                securityType)
-        if (Build.VERSION.SDK_INT >= 31) setChannels(builder, channels) else {
-            val (band, channel) = requireSingleBand()
-            if (channel == 0) setBand(builder, band) else setChannel(builder, channel, band)
-        }
+            securityType)
+        setChannelsCompat(builder, channels)
         setBssid(builder, bssid?.toPlatform())
         setMaxNumberOfClients(builder, maxNumberOfClients)
         setShutdownTimeoutMillis(builder, shutdownTimeoutMillis)
diff --git a/mobile/src/main/java/be/mygod/vpnhotspot/net/wifi/WifiApDialogFragment.kt b/mobile/src/main/java/be/mygod/vpnhotspot/net/wifi/WifiApDialogFragment.kt
index de86fd88..fcb13a4c 100644
--- a/mobile/src/main/java/be/mygod/vpnhotspot/net/wifi/WifiApDialogFragment.kt
+++ b/mobile/src/main/java/be/mygod/vpnhotspot/net/wifi/WifiApDialogFragment.kt
@@ -95,6 +95,19 @@ class WifiApDialogFragment : AlertDialogFragment<WifiApDialogFragment.Arg, WifiA
     private val currentChannels5G get() = if (arg.p2pMode && !RepeaterService.safeMode) p2pChannels else channels5G
     override val ret get() = Arg(generateConfig())
 
+    private fun generateChannels() = SparseIntArray(4).apply {
+        for ((band, spinner) in arrayOf(SoftApConfigurationCompat.BAND_2GHZ to dialogView.band2G,
+            SoftApConfigurationCompat.BAND_5GHZ to dialogView.band5G,
+            SoftApConfigurationCompat.BAND_6GHZ to dialogView.band6G,
+            SoftApConfigurationCompat.BAND_60GHZ to dialogView.band60G)) {
+            val channel = (spinner.selectedItem as ChannelOption?)?.channel
+            if (channel != null && channel >= 0) append(band, channel)
+        }
+    }.let {
+        if (arg.p2pMode || Build.VERSION.SDK_INT < 31 || !dialogView.bridgedMode.isChecked || it.size() > 2) {
+            SoftApConfigurationCompat.optimizeChannels(it)
+        } else it
+    }
     private fun generateConfig(full: Boolean = true) = base.copy(
             ssid = dialogView.ssid.text.toString(),
             passphrase = if (dialogView.password.length() != 0) dialogView.password.text.toString() else null).apply {
@@ -107,19 +120,7 @@ class WifiApDialogFragment : AlertDialogFragment<WifiApDialogFragment.Arg, WifiA
             shutdownTimeoutMillis = dialogView.timeout.text.let { text ->
                 if (text.isNullOrEmpty()) 0 else text.toString().toLong()
             }
-            if (Build.VERSION.SDK_INT >= 23 || arg.p2pMode) {
-                val channels = SparseIntArray(4)
-                for ((band, spinner) in arrayOf(SoftApConfigurationCompat.BAND_2GHZ to dialogView.band2G,
-                    SoftApConfigurationCompat.BAND_5GHZ to dialogView.band5G,
-                    SoftApConfigurationCompat.BAND_6GHZ to dialogView.band6G,
-                    SoftApConfigurationCompat.BAND_60GHZ to dialogView.band60G)) {
-                    val channel = (spinner.selectedItem as ChannelOption?)?.channel
-                    if (channel != null && channel >= 0) channels.append(band, channel)
-                }
-                if (!arg.p2pMode && Build.VERSION.SDK_INT >= 31 && dialogView.bridgedMode.isChecked) {
-                    this.channels = channels
-                } else optimizeChannels(channels)
-            }
+            if (Build.VERSION.SDK_INT >= 23 || arg.p2pMode) channels = generateChannels()
             bssid = if (dialogView.bssid.length() != 0) {
                 MacAddressCompat.fromString(dialogView.bssid.text.toString())
             } else null
@@ -291,29 +292,28 @@ class WifiApDialogFragment : AlertDialogFragment<WifiApDialogFragment.Arg, WifiA
             }
         }
         dialogView.timeoutWrapper.error = timeoutError
-        val isBandValid = when {
-            arg.p2pMode || Build.VERSION.SDK_INT in 23 until 30 -> {
-                val option5G = dialogView.band5G.selectedItem
-                when (dialogView.band2G.selectedItem) {
-                    is ChannelOption.Disabled -> option5G !is ChannelOption.Disabled &&
-                            (!arg.p2pMode || RepeaterService.safeMode || option5G !is ChannelOption.Auto)
-                    is ChannelOption.Auto ->
-                        (arg.p2pMode || Build.VERSION.SDK_INT >= 28) && option5G is ChannelOption.Auto ||
-                                (!arg.p2pMode || RepeaterService.safeMode) && option5G is ChannelOption.Disabled
-                    else -> option5G is ChannelOption.Disabled
-                }
+        val bandError = if (arg.p2pMode || Build.VERSION.SDK_INT <= 30) {
+            val option5G = dialogView.band5G.selectedItem
+            val valid = when (dialogView.band2G.selectedItem) {
+                is ChannelOption.Disabled -> option5G !is ChannelOption.Disabled &&
+                        (!arg.p2pMode || RepeaterService.safeMode || option5G !is ChannelOption.Auto)
+                is ChannelOption.Auto ->
+                    (arg.p2pMode || Build.VERSION.SDK_INT >= 28) && option5G is ChannelOption.Auto ||
+                            (!arg.p2pMode || RepeaterService.safeMode) && option5G is ChannelOption.Disabled
+                else -> option5G is ChannelOption.Disabled
             }
-            Build.VERSION.SDK_INT == 30 -> {
-                var expected = 1
-                var set = 0
-                for (s in arrayOf(dialogView.band2G, dialogView.band5G, dialogView.band6G)) when (s.selectedItem) {
-                    is ChannelOption.Auto -> expected = 0
-                    !is ChannelOption.Disabled -> ++set
-                }
-                set == expected
+            if (valid) null else ""
+        } else {
+            if (Build.VERSION.SDK_INT >= 31) setBridgedMode()
+            try {
+                SoftApConfigurationCompat.testPlatformValidity(generateChannels())
+                null
+            } catch (e: Exception) {
+                e.readableMessage
             }
-            else -> setBridgedMode()
         }
+        dialogView.bandError.isGone = bandError.isNullOrEmpty()
+        dialogView.bandError.text = bandError
         dialogView.bssidWrapper.error = null
         val bssidValid = dialogView.bssid.length() == 0 || try {
             MacAddressCompat.fromString(dialogView.bssid.text.toString())
@@ -353,7 +353,7 @@ class WifiApDialogFragment : AlertDialogFragment<WifiApDialogFragment.Arg, WifiA
         } else true
         val canCopy = timeoutError == null && bssidValid && maxClientError == null && listsNoError
         (dialog as? AlertDialog)?.getButton(DialogInterface.BUTTON_POSITIVE)?.isEnabled =
-                ssidLength in 1..32 && passwordValid && isBandValid && canCopy
+                ssidLength in 1..32 && passwordValid && bandError == null && canCopy
         dialogView.toolbar.menu.findItem(android.R.id.copy).isEnabled = canCopy
     }
 
diff --git a/mobile/src/main/res/layout/dialog_wifi_ap.xml b/mobile/src/main/res/layout/dialog_wifi_ap.xml
index cff941e6..952d3cb0 100644
--- a/mobile/src/main/res/layout/dialog_wifi_ap.xml
+++ b/mobile/src/main/res/layout/dialog_wifi_ap.xml
@@ -16,11 +16,13 @@
      See the License for the specific language governing permissions and
      limitations under the License.
 -->
-<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
-              xmlns:app="http://schemas.android.com/apk/res-auto"
-              android:layout_width="300sp"
-              android:layout_height="wrap_content"
-              android:orientation="vertical">
+<LinearLayout
+    xmlns:android="http://schemas.android.com/apk/res/android"
+    xmlns:app="http://schemas.android.com/apk/res-auto"
+    xmlns:tools="http://schemas.android.com/tools"
+    android:layout_width="300sp"
+    android:layout_height="wrap_content"
+    android:orientation="vertical">
     <com.google.android.material.appbar.MaterialToolbar
         android:id="@+id/toolbar"
         android:layout_width="match_parent"
@@ -208,6 +210,16 @@
                     android:layout_marginTop="8dip"
                     android:minHeight="@dimen/touch_target_min"
                     android:text="@string/wifi_bridged_mode" />
+                <TextView
+                    android:id="@+id/band_error"
+                    android:layout_width="match_parent"
+                    android:layout_height="wrap_content"
+                    android:layout_marginTop="8dip"
+                    android:paddingStart="8dp"
+                    android:textAppearance="@style/TextAppearance.Design.Error"
+                    android:visibility="gone"
+                    tools:text="error text placeholder"
+                    tools:visibility="visible"/>
                 <Switch
                     android:id="@+id/bridged_mode_opportunistic_shutdown"
                     style="@style/wifi_item_label"