fix: apply LoRa config changes live without rebooting

src/DisplayFormatters.cpp

@@ -4,7 +4,8 @@ const char *DisplayFormatters::getModemPresetDisplayName(meshtastic_Config_LoRaC
                                                          bool usePreset)
 {
 
-    // If use_preset is false, always return "Custom"
+    // If use_preset is false, always return "Custom" — callers such as RadioInterface and Channels
+    // rely on this being a stable literal for channel-name hashing and default-channel detection.
     if (!usePreset) {
         return "Custom";
     }

src/graphics/draw/DebugRenderer.cpp

@@ -408,15 +408,23 @@ void drawLoRaFocused(OLEDDisplay *display, OLEDDisplayUiState *state, int16_t x,
     display->drawString(nameX, getTextPositions(display)[line++], device_role);
 
     // === Third Row: Radio Preset ===
-    auto mode = DisplayFormatters::getModemPresetDisplayName(config.lora.modem_preset, false, config.lora.use_preset);
+    // For custom modem settings show the actual parameters; for presets use the preset name.
+    char modeStr[16];
+    if (!config.lora.use_preset) {
+        snprintf(modeStr, sizeof(modeStr), "BW%u-SF%u-CR%u", static_cast<unsigned>(config.lora.bandwidth),
+                 static_cast<unsigned>(config.lora.spread_factor), static_cast<unsigned>(config.lora.coding_rate));
+    } else {
+        strncpy(modeStr, DisplayFormatters::getModemPresetDisplayName(config.lora.modem_preset, false, true), sizeof(modeStr) - 1);
+        modeStr[sizeof(modeStr) - 1] = '\0';
+    }
 
     char regionradiopreset[25];
     const char *region = myRegion ? myRegion->name : NULL;
     if (region != nullptr) {
         if (currentResolution == ScreenResolution::UltraLow) {
             snprintf(regionradiopreset, sizeof(regionradiopreset), "%s", region);
         } else {
-            snprintf(regionradiopreset, sizeof(regionradiopreset), "%s/%s", region, mode);
+            snprintf(regionradiopreset, sizeof(regionradiopreset), "%s/%s", region, modeStr);
         }
     }
     textWidth = display->getStringWidth(regionradiopreset);

src/modules/AdminModule.cpp

@@ -25,6 +25,7 @@
 #include "Default.h"
 #include "MeshRadio.h"
 #include "TypeConversions.h"
+#include "mesh/RadioLibInterface.h"
 
 #if !MESHTASTIC_EXCLUDE_MQTT
 #include "mqtt/MQTT.h"
@@ -197,10 +198,35 @@ bool AdminModule::handleReceivedProtobuf(const meshtastic_MeshPacket &mp, meshta
         handleSetOwner(r->set_owner);
         break;
 
-    case meshtastic_AdminMessage_set_config_tag:
+    case meshtastic_AdminMessage_set_config_tag: {
         LOG_DEBUG("Client set config");
-        handleSetConfig(r->set_config);
+
+        // Non-LoRa configs need no further validation.
+        if (r->set_config.which_payload_variant != meshtastic_Config_lora_tag) {
+            LOG_DEBUG("Non-LoRa config, applying directly");
+            handleSetConfig(r->set_config);
+            break;
+        }
+
+        // Only LORA_24 requires hardware capability validation.
+        if (r->set_config.payload_variant.lora.region != meshtastic_Config_LoRaConfig_RegionCode_LORA_24) {
+            LOG_DEBUG("LoRa config, region is not LORA_24, applying directly");
+            handleSetConfig(r->set_config);
+            break;
+        }
+
+        // Hardware supports 2.4 GHz — apply the config.
+        // Fail closed: null instance is treated as incapable.
+        if (RadioLibInterface::instance && RadioLibInterface::instance->wideLora()) {
+            LOG_DEBUG("LORA_24 requested, radio hardware supports 2.4 GHz, applying");
+            handleSetConfig(r->set_config);
+            break;
+        }
+
+        LOG_WARN("Radio hardware does not support 2.4 GHz; rejecting LORA_24 region");
+        myReply = allocErrorResponse(meshtastic_Routing_Error_BAD_REQUEST, &mp);
         break;
+    }
 
     case meshtastic_AdminMessage_set_module_config_tag:
         LOG_DEBUG("Client set module config");
@@ -768,17 +794,10 @@ void AdminModule::handleSetConfig(const meshtastic_Config &c)
             validatedLora.spread_factor = LORA_SF_DEFAULT;
         }
 
-        // If no lora radio parameters change, don't need to reboot
-        if (oldLoraConfig.use_preset == validatedLora.use_preset && oldLoraConfig.region == validatedLora.region &&
-            oldLoraConfig.modem_preset == validatedLora.modem_preset && oldLoraConfig.bandwidth == validatedLora.bandwidth &&
-            oldLoraConfig.spread_factor == validatedLora.spread_factor &&
-            oldLoraConfig.coding_rate == validatedLora.coding_rate && oldLoraConfig.tx_power == validatedLora.tx_power &&
-            oldLoraConfig.frequency_offset == validatedLora.frequency_offset &&
-            oldLoraConfig.override_frequency == validatedLora.override_frequency &&
-            oldLoraConfig.channel_num == validatedLora.channel_num &&
-            oldLoraConfig.sx126x_rx_boosted_gain == validatedLora.sx126x_rx_boosted_gain) {
-            requiresReboot = false;
-        }
+        // LoRa radio changes are applied live via the configChanged observer which calls reconfigure().
+        // reconfigure() puts the radio in standby, reprograms all modem parameters, and restarts receive.
+        // sx126x_rx_boosted_gain is only applied during init(), so a reboot is still required for that setting.
+        requiresReboot = (oldLoraConfig.sx126x_rx_boosted_gain != validatedLora.sx126x_rx_boosted_gain);
 
 #if defined(ARCH_PORTDUINO)
         // If running on portduino and using SimRadio, do not require reboot