diff --git a/lib/BlueSCSI_platform_RP2MCU/BlueSCSI_platform_network.cpp b/lib/BlueSCSI_platform_RP2MCU/BlueSCSI_platform_network.cpp
index 12771629..f2cd9698 100644
--- a/lib/BlueSCSI_platform_RP2MCU/BlueSCSI_platform_network.cpp
+++ b/lib/BlueSCSI_platform_RP2MCU/BlueSCSI_platform_network.cpp
@@ -42,6 +42,11 @@ static const char defaultMAC[] = { 0x00, 0x80, 0x19, 0xc0, 0xff, 0xee };
 
 static bool network_in_use = false;
 
+// Whether the WiFi interface answered the boot-time check in
+// platform_network_iface_check(). The RM2 module is optional on Ultra,
+// so this stays false until the module is actually detected.
+static bool network_iface_present = false;
+
 // WiFi reconnection state (file-static so wifi_join can reset on credential change)
 static uint32_t wifi_reconnect_time = 0;
 static uint32_t wifi_reconnect_interval = WIFI_RECONNECT_INTERVAL;
@@ -51,7 +56,7 @@ bool platform_network_supported()
 {
 	/* from cores/rp2040/RP2040Support.h */
 #if defined(BLUESCSI_ULTRA)
-	return true;
+	return network_iface_present;
 #elif !defined(PICO_CYW43_SUPPORTED) || defined(BLUESCSI_ULTRA_WIDE)
 	return false;
 #else
@@ -244,7 +249,8 @@ bool platform_network_iface_check()
 {
 	cyw43_deinit(&cyw43_state);
 	cyw43_init(&cyw43_state);
-	return 0 == cyw43_gpio_set(&cyw43_state, PICO_W_GPIO_LED_PIN, 1);
+	network_iface_present = (0 == cyw43_gpio_set(&cyw43_state, PICO_W_GPIO_LED_PIN, 1));
+	return network_iface_present;
 }
 
 void platform_network_deinit()
diff --git a/src/BlueSCSI.cpp b/src/BlueSCSI.cpp
index 2f86e289..00c26474 100644
--- a/src/BlueSCSI.cpp
+++ b/src/BlueSCSI.cpp
@@ -1,6 +1,6 @@
 /*
  *  BlueSCSI v2
- *  Copyright (c) 2023-2025 Eric Helgeson, Androda, and contributors.
+ *  Copyright (c) 2023-2026 Eric Helgeson, Androda, and contributors.
  *
  *  This project is based on ZuluSCSI, BlueSCSI v1, and SCSI2SD:
  *
@@ -1313,6 +1313,26 @@ STATIC_TESTABLE void bluescsi_setup_sd_card(bool wait_for_card = true)
 
 #ifdef RECLOCKING_SUPPORTED
     bluescsi_speed_grade_t speed_grade = (bluescsi_speed_grade_t) g_scsi_settings.getSystem()->speedGrade;
+#if defined(BLUESCSI_ULTRA) && defined(BLUESCSI_NETWORK)
+    // The RM2 is reached over a PIO SPI bus whose divider is a compile-time
+    // constant sized for the stock clock, so the bus speed scales with clk_sys.
+    // Past the WifiRM2 grade the module stops answering, and it fails silently:
+    // cyw43_wifi_on() fails inside cyw43_wifi_set_up(), which returns void, so
+    // the interface is left down and every later scan/join returns -4 with
+    // nothing logged. Measured on an Ultra: the RM2 answers at 150MHz and is
+    // dead at 251MHz (TurboMax). When an RM2 is actually installed its clock wins
+    // over the configured grade - platform_network_supported() is only true
+    // here once the module answered the boot-time probe.
+    if (platform_network_supported() && speed_grade != SPEED_GRADE_WIFI_RM2)
+    {
+      logmsg("RM2 detected: overriding SpeedGrade \"", g_scsi_settings.getSpeedGradeString(),
+             "\" with \"WifiRM2\" - the RM2 does not respond at higher clocks");
+      // Update the setting itself, not just the local, so the reclock log below
+      // and every other reader report the grade actually in force.
+      speed_grade = SPEED_GRADE_WIFI_RM2;
+      g_scsi_settings.getSystem()->speedGrade = SPEED_GRADE_WIFI_RM2;
+    }
+#endif
     if (speed_grade != bluescsi_speed_grade_t::SPEED_GRADE_DEFAULT)
     { 
       logmsg("Speed grade set to ", g_scsi_settings.getSpeedGradeString(), " reclocking system");