🔧 Bambu Lab Troubleshooting

🚨 Printer does not connect

If your Bambu Lab printer does not connect, FIRST read the section above about blocking! If you have the correct firmware version (before January 2025 or rolled back), follow this step-by-step guide.

✅ Checklist (check in the specified order)

0️⃣ FIRMWARE VERSION CHECK - CRITICAL!

On printer touchscreen:

1. Go to: Settings → About printer → Firmware version
2. Check firmware release date
3. If firmware is January 2025 or newer - see section above about blocking!

⚠️ This check is MANDATORY before all other steps!

1️⃣ Developer mode / LAN Mode check

On printer touchscreen:

1. Go to: Settings → Network → LAN Only Mode (or Developer mode)
2. Make sure the switch is ON (green)
3. Write down Access Code (8 digits) - it's permanent, doesn't change

⚠️ IMPORTANT:

• After enabling developer mode restart printer (turn off and on)
• Access Code must be exactly 8 digits
• Is code case sensitive? NO - only digits

📌 For old firmware (before 1.09.00):

• In firmware 1.08.x and earlier this mode is simply called "LAN Mode"
• App will automatically try both protocols (MQTTS and MQTT) for compatibility
• Functionality is the same - just different name

2️⃣ IP address check

On printer touchscreen:

1. Go to: Settings → Network → Network information
2. Find IP address (for example, 192.168.1.100)
3. Make sure IP address starts with the same subnet as your PC

Printer availability check:

# Windows (PowerShell или CMD)
ping 192.168.1.100

# Should get response:# Reply from 192.168.1.100: bytes=32 time=1ms TTL=64

❌ If ping fails:

• Printer and PC in different networks
• Router blocks connections
• Wrong IP address

3️⃣ Serial number check

Serial number format: 01P00A123456789 (15 characters)

Where to find:

• On sticker on printer body
• In app Bambu Handy: Settings → About printer
• On touchscreen: Settings → About printer

⚠️ IMPORTANT:

• Serial number must be exact
• Check for extra spaces at beginning/end
• Character case matters: 01P00A (uppercase letters)

4️⃣ Firewall check

Bambu Lab uses port 8883 for MQTT connection.

Windows:

1. Open Windows Firewall (Windows Defender Firewall)
2. Go to: Advanced settings → Outbound rules
3. Find application 3D Printer Control Panel
4. Make sure it's allowed

Or create rule manually:

Port: 8883Protocol: TCPDirection: OutboundAction: Allow

Quick check (temporarily disable firewall):

• NOT RECOMMENDED for permanent use
• Only for diagnostics

5️⃣ MQTT connection check

Use MQTT Explorer (free tool):

1. Download: mqtt-explorer.com
2. Configure connection:
   • Protocol: mqtts://
   • Host: Your printer IP
   • Port: 8883
   • Username: bblp
   • Password: your Access Code
   • SSL/TLS: Enabled, but without certificate verification
3. Click Connect

✅ If connects - problem in app (restart app)
❌ If doesn't connect - problem in printer settings or network

🔍 Common problems

❌ "Connection timeout - timeout exceeded"

Causes:

1. Printer is off or sleeping
2. Wrong IP address
3. Firewall blocks port 8883
4. Printer and PC in different subnets

Solution:

• Check that printer is on and not in sleep mode
• Check IP address (may change after router reboot)
• Temporarily disable firewall for testing
• Use static IP for printer in router settings

❌ "Printer unavailable. Check IP address"

Causes:

1. Wrong IP address
2. Printer changed IP (DHCP)
3. Printer is off

Solution:

• Check IP address on printer screen
• Set up static IP in router
• Make sure printer is on

❌ "Invalid Access Code"

Causes:

1. Code written incorrectly
2. Developer mode was turned off and on again (code may have changed)
3. Extra spaces when entering

Solution:

• Check code on printer screen again
• Copy code without spaces
• Try turning off and on developer mode again

❌ "Not authorized or authorization errors"

Causes:

1. Developer mode is off
2. Invalid Access Code
3. Printer wasn't rebooted after enabling developer mode

Solution:

1. Check that developer mode is enabled
2. Reboot printer (turn off and on power)
3. Check Access Code
4. Wait 30-60 seconds after turning on printer

🛠️ Step-by-step diagnostics

If printer still doesn't connect, follow these steps in order:

Step 1: Full reboot

1. Close 3D Printer Control Panel app
2. Turn off printer (from outlet)
3. Wait 30 seconds
4. Turn on printer
5. Wait for full boot (screen ready)
6. Start app again

Step 2: Developer mode check

1. On printer screen: Settings → Network → Developer mode
2. If off - turn on
3. Reboot printer again
4. Write down Access Code

Step 3: Ping test

ping <printer_IP> -t

Should get responses. If not - network problem.

Step 4: Port 8883 check

Windows:

Test-NetConnection -ComputerName <printer_IP> -Port 8883

Linux/Mac:

nc -zv <printer_IP> 8883

If port is closed or filtered - problem in firewall or router.

Step 5: Recreate printer in app

1. Delete printer from app
2. Restart app
3. Add printer again with correct data:
   • Type: Bambu Lab
   • IP: verified IP
   • Access Code: verified code (8 digits)
   • Serial Number: exact serial number

🌐 Network settings

Recommended configuration

1. Static IP for printer

Configure in router DHCP reservation (DHCP Reservation):

• Binding printer MAC address to permanent IP
• IP won't change after reboot

2. Firewall setup

Create exception for:

• Application: 3D Printer Control Panel.exe
• Port: 8883
• Protocol: TCP
• Direction: Outbound

3. Router

Some routers have inter-network protection (AP Isolation):

• Make sure AP Isolation is off
• Check Guest Network - printer shouldn't be on guest network

📊 Logs and diagnostics

Viewing logs in app

1. Open 3D Printer Control Panel
2. Click button "📋 Event log" at bottom
3. Find error messages when connecting
4. Copy error text for analysis

Typical error messages

✅ Successful connection:

✅ Bambu Lab: <Name> connected successfully

❌ Timeout error:

❌ Connection timeout - connection timeout exceeded (10 sec)

Solution: Check network and firewall

❌ ECONNREFUSED error:

❌ Printer unavailable. Check IP address and make sure printer is on.

Solution: Check IP and if printer is on

❌ Authorization error:

❌ Invalid Access Code. Check code in printer settings.

Solution: Check Access Code and developer mode

🔄 Alternative solutions

Option 1: Using Bambu Handy app

To check that printer works correctly:

1. Install Bambu Handy on phone
2. Connect to printer via LAN Mode
3. If connects - problem in PC/app settings
4. If doesn't connect - problem in printer

Option 2: Using Bambu Studio

1. Open Bambu Studio
2. Try connecting via LAN Mode
3. If works - compare settings with app

📞 Getting help

If nothing helped, prepare the following information:

Diagnostic data:

1. Printer model: (X1, X1C, P1P, P1S etc.)
2. Printer IP address:3. Printer firmware version:4. PC operating system:5. App version:6. Error log screenshot:7. Ping command result:8. Developer mode enabled: Yes/No9. Printer connects via Bambu Handy: Yes/No

Where to contact:

• GitHub Issues: github.com/Tombraider2006/KCP/issues
• Telegram: @Tom_Tomich

⚡ Quick solution (90% of cases)

Most problems are solved like this:

1. ✅ Reboot printer (turn off and on power)
2. ✅ Check developer mode on printer screen
3. ✅ Check IP address (may change)
4. ✅ Delete and add printer again in app
5. ✅ Restart app

🎓 Additional information

MQTT connection technical details:

• Protocol:
  • MQTTS (MQTT over TLS/SSL) - for firmware 1.09.00+
  • MQTT (without encryption) - for firmware 1.08.x and earlier
  • App automatically tries both protocols
• Port: 8883
• Username: bblp (standard for all printers)
• Password: Access Code (8 digits)
• Subscription topic: device/<SerialNumber>/report
• Command topic: device/<SerialNumber>/request

Network requirements:

• Printer and PC must be in same local network
• Router shouldn't block port 8883
• Multicast must be allowed (for printer discovery)
• AP Isolation must be off

✅ Checklist before seeking help

Before seeking help, make sure you completed everything from this list:

• Developer mode enabled on printer
• Printer rebooted after enabling developer mode
• Access Code correct (8 digits, no spaces)
• Serial number correct (15 characters)
• IP address correct and current
• Ping to printer successful
• Firewall doesn't block app
• Port 8883 open
• Printer and PC in same network
• App restarted
• Printer deleted and added again in app
• Error logs viewed in app
• Bambu Handy can connect to printer

Successful connection! 🖨️🎋