diff --git a/components/esp_modem/examples/simple_cmux_client/sdkconfig.ci.sim800_cmux b/components/esp_modem/examples/simple_cmux_client/sdkconfig.ci.sim800_cmux
index 1c7e2296f1b..18b02189f20 100644
--- a/components/esp_modem/examples/simple_cmux_client/sdkconfig.ci.sim800_cmux
+++ b/components/esp_modem/examples/simple_cmux_client/sdkconfig.ci.sim800_cmux
@@ -14,3 +14,11 @@ CONFIG_ESP_SYSTEM_PANIC_PRINT_HALT=y
 CONFIG_ESP32_PANIC_PRINT_HALT=y
 CONFIG_COMPILER_CXX_EXCEPTIONS=y
 CONFIG_ESP_MAIN_TASK_STACK_SIZE=8192
+CONFIG_EXAMPLE_CLOSE_CMUX_AT_END=y
+CONFIG_LOG_DEFAULT_LEVEL_DEBUG=y
+# CONFIG_LOG_DEFAULT_LEVEL_VERBOSE is not set
+CONFIG_LOG_DEFAULT_LEVEL=4
+CONFIG_LOG_MAXIMUM_EQUALS_DEFAULT=y
+# CONFIG_LOG_MAXIMUM_LEVEL_VERBOSE is not set
+CONFIG_LOG_MAXIMUM_LEVEL=4
+# CONFIG_LOG_MASTER_LEVEL is not set
diff --git a/components/esp_modem/src/esp_modem_cmux.cpp b/components/esp_modem/src/esp_modem_cmux.cpp
index 1ce67a61f61..cf36c5e43f5 100644
--- a/components/esp_modem/src/esp_modem_cmux.cpp
+++ b/components/esp_modem/src/esp_modem_cmux.cpp
@@ -116,8 +116,10 @@ struct CMux::CMuxFrame {
 bool CMux::data_available(uint8_t *data, size_t len)
 {
     if (data && (type & FT_UIH) == FT_UIH && len > 0 && dlci > 0) { // valid payload on a virtual term
+        ESP_LOGW("CMUX", "%d", __LINE__);
         int virtual_term = dlci - 1;
         if (virtual_term < MAX_TERMINALS_NUM && read_cb[virtual_term]) {
+            ESP_LOGW("CMUX", "%d", __LINE__);
             // Post partial data (or defragment to post on CMUX footer)
 #ifdef DEFRAGMENT_CMUX_PAYLOAD
             if (payload_start == nullptr) {
@@ -129,30 +131,40 @@ bool CMux::data_available(uint8_t *data, size_t len)
             read_cb[virtual_term](data, len);
 #endif
         } else {
+            ESP_LOGW("CMUX", "%d", __LINE__);
             return false;
         }
     } else if (data == nullptr && type == (FT_UA | PF) && len == 0) { // notify the initial SABM command
+        ESP_LOGW("CMUX", "%d", __LINE__);
         Scoped<Lock> l(lock);
         sabm_ack = dlci;
     } else if (data == nullptr && dlci > 0) {
+        ESP_LOGW("CMUX", "%d", __LINE__);
         int virtual_term = dlci - 1;
         if (virtual_term < MAX_TERMINALS_NUM && read_cb[virtual_term]) {
+            ESP_LOGW("CMUX", "%d", __LINE__);
 #ifdef DEFRAGMENT_CMUX_PAYLOAD
             read_cb[virtual_term](payload_start, total_payload_size);
 #endif
         } else {
+            ESP_LOGW("CMUX", "%d", __LINE__);
             return false;
         }
     } else if ((type & FT_UIH) == FT_UIH && dlci == 0) { // notify the internal DISC command
+        ESP_LOG_BUFFER_HEXDUMP("type 0xEF", data, len, ESP_LOG_INFO);
         if (len > 0 && (data[0] & 0xE1) == 0xE1) {
+            ESP_LOGW("CMUX", "%d", __LINE__);
             // Not a DISC, ignore (MSC frame)
             return true;
         }
+        ESP_LOGW("CMUX", "%d", __LINE__);
         Scoped<Lock> l(lock);
         sabm_ack = dlci;
     } else {
+        ESP_LOGW("CMUX", "%d", __LINE__);
         return false;
     }
+    ESP_LOGW("CMUX", "%d", __LINE__);
     return true;
 }
 
@@ -234,6 +246,7 @@ bool CMux::on_header(CMuxFrame &frame)
     // since CRC could be evaluated after the frame payload gets received
     if (dlci > MAX_TERMINALS_NUM || (frame_header[1] & 0x01) == 0 ||
             (((type & FT_UIH) != FT_UIH) &&  type != (FT_UA | PF) ) ) {
+        ESP_LOGI("CMUX", "[1]:%02x [2]:%02x [3]:%02x", frame_header[1], frame_header[2], frame_header[3]);
         recover_protocol(protocol_mismatch_reason::UNEXPECTED_HEADER);
         return true;
     }
@@ -340,7 +353,7 @@ bool CMux::on_cmux_data(uint8_t *data, size_t actual_len)
         actual_len = term->read(data, buffer.size);
 #endif
     }
-    ESP_LOG_BUFFER_HEXDUMP("CMUX Received", data, actual_len, ESP_LOG_VERBOSE);
+    ESP_LOG_BUFFER_HEXDUMP("CMUX Received", data, actual_len, ESP_LOG_INFO);
     CMuxFrame frame = { .ptr = data, .len = actual_len };
     while (frame.len > 0) {
         switch (state) {