The Brother MFC-L3770CDW is a reliable color laser all-in-one printer, but like any printer, it can occasionally experience problems such as paper jams, offline status, print quality issues, toner errors, Wi-Fi connectivity failures, or scanning problems. Fortunately, most of these issues can be resolved without calling technical support.

This comprehensive Brother MFC-L3770CDW troubleshooting guide walks you through the most common problems, explains why they happen, and provides step-by-step solutions for Windows, macOS, and mobile users. It also includes preventive maintenance tips to help keep your printer operating efficiently. Brother also recommends keeping the printer firmware updated for optimal performance and compatibility.

What You’ll Learn

• Common Brother MFC-L3770CDW problems
• Printer won’t print solutions
• Offline printer fixes
• Paper jam troubleshooting
• Toner and drum errors
• Print quality improvements
• Wi-Fi connection problems
• Scanner troubleshooting
• Driver and firmware fixes
• Preventive maintenance tips
• Frequently asked questions

Common Brother MFC-L3770CDW Problems

Most issues fall into one of these categories:

Problem	Common Cause
Printer Offline	Network or driver issue
Paper Jam	Misaligned or damaged paper
Toner Error	Empty or improperly installed toner
Replace Drum	The drum unit reached end of life
Poor Print Quality	Dirty drum, low toner, or calibration needed
Scanner Not Working	Driver or connection issue
Wireless Connection Lost	Router or network settings
Slow Printing	High-resolution jobs or outdated firmware

Identifying the exact symptom makes troubleshooting much easier.

Brother MFC-L3770CDW Not Printing

If your printer powers on but refuses to print, start with these basic checks.

Verify Printer Status

• Ensure the printer is powered on.
• Confirm there are no error messages on the LCD.
• Check that paper is loaded correctly.
• Verify toner cartridges are installed properly.

Clear the print queue.

Sometimes a stuck print job blocks all future documents.

Windows

1. Open Settings
2. Select Printers & Scanners
3. Choose Brother MFC-L3770CDW
4. Open the print queue
5. Cancel all pending jobs

Mac

1. Open System Settings
2. Select Printers & Scanners
3. Open the queue
4. Remove stalled print jobs

Restart Your Devices

Restart:

• Printer
• Computer
• Wi-Fi router

This simple step often restores communication between devices.

Brother MFC-L3770CDW Offline Troubleshooting

An offline printer usually indicates a communication problem.

Check the network connection.

Confirm that:

• The printer is connected to the correct Wi-Fi network.
• Your computer is connected to the same network.
• The router is functioning properly.

Set the Printer as default.

Windows users should verify that the Brother printer is selected as the default printer.

Disable “Use Printer Offline”

Open printer settings and make sure the Use Printer Offline option is unchecked.

Brother MFC-L3770CDW Paper Jam Troubleshooting

Paper jams are common but easy to fix.

Causes

• Incorrect paper size
• Overfilled paper tray
• Wrinkled paper
• Dirty paper feed rollers

How to Remove a Paper Jam

1. Turn off the printer.
2. Open the front cover.
3. Remove the toner and drum assembly if necessary.
4. Carefully pull out jammed paper.
5. Inspect the rear access area.
6. Reinstall components.
7. Restart the printer.

Avoid pulling paper forcefully, as this may damage internal rollers.

Brother MFC-L3770CDW Toner and Drum Troubleshooting

Laser printers rely on separate toner cartridges and drum units.

Common messages include:

• Toner Low
• Replace Toner
• Drum End Soon
• Replace Drum
• Drum Stop

If you’ve installed a new drum but still see drum-related messages, the drum counter may need to be reset according to Brother’s maintenance instructions.

Check Toner Installation

Remove each toner cartridge and verify:

• It clicks securely into place.
• Protective packaging has been removed.
• The cartridge is compatible with your printer.

Inspect the Drum Unit

A worn drum may cause the following:

• Vertical streaks
• Faded pages
• Repeating marks
• Missing colors

Replace the drum when its service life has ended.

Brother MFC-L3770CDW Print Quality Problems

Poor print quality usually indicates maintenance is needed.

Common symptoms include:

• Faded printing
• White lines
• Smudges
• Blurry text
• Uneven colors

Solutions

• Run automatic color calibration.
• Clean the corona wires.
• Check toner levels.
• Replace worn drum units.
• Print a test page.

Brother also recommends cleaning the LED print head periodically if print quality declines.

Brother MFC-L3770CDW Wi-Fi Troubleshooting

Wireless issues often occur after changing routers or passwords.

Reconnect to Wi-Fi

1. Open Network Settings.
2. Select Wireless Setup Wizard.
3. Choose your Wi-Fi network.
4. Enter the password.
5. Confirm the connection.

If signal strength is poor:

• Move the printer closer to the router.
• Reduce wireless interference.
• Restart the router.

Brother MFC-L3770CDW Scanner Not Working

Scanning issues may result from outdated software or network communication problems.

Verify Scanner Drivers

Update:

• Brother printer driver
• Brother scanner driver
• Brother iPrint&Scan software

Restart your computer after installation.

Check Network Discovery

Network scanning requires both the computer and printer to be visible on the same network.

Brother MFC-L3770CDW Driver and Firmware Troubleshooting

Outdated software can cause the following:

• Printing failures
• Scanning errors
• Network problems
• Compatibility issues after Windows updates

Install the latest:

• Printer driver
• Scanner driver
• Firmware

Brother specifically advises updating firmware for the best performance and provides fixes for issues that can occur after Windows updates.

Resetting the Brother MFC-L3770CDW

A restart can clear temporary software glitches.

Soft Reset

1. Turn off the printer.
2. Unplug the power cord.
3. Wait one minute.
4. Plug the printer back in.
5. Turn it on.

If problems persist, review the printer’s maintenance menu or Brother support guidance before performing more advanced resets.

Preventive Maintenance Tips

Regular maintenance helps avoid unexpected printer failures.

Best practices include:

• Clean the printer monthly.
• Store paper in a dry environment.
• Use high-quality toner cartridges.
• Update firmware regularly.
• Replace drum units when recommended.
• Clean paper feed rollers periodically.
• Perform color calibration after replacing consumables.
• Keep ventilation openings free of dust.

Quick Answers

Why is my Brother MFC-L3770CDW not printing?

The most common causes are an offline printer, stuck print queue, outdated driver, low toner, or network communication issues.

Why does my Brother printer say Replace Drum?

The drum unit has reached its expected service life, or the drum counter needs to be reset after replacement.

How do I reconnect my Brother MFC-L3770CDW to Wi-Fi?

Use the printer’s Wireless Setup Wizard, reconnect it to your wireless network, and ensure your computer is connected to the same Wi-Fi.

Frequently Asked Questions

Why is my Brother MFC-L3770CDW printing blank pages?

Blank pages are usually caused by empty toner cartridges, improperly installed toner, protective seals left on new cartridges, or drum issues.

Can outdated firmware cause printing problems?

Yes. Firmware updates often resolve compatibility issues, improve printer stability, and fix software bugs.

How often should I replace the drum unit?

The drum should be replaced when the printer displays Replace Drum or Drum End Soon, or when print quality noticeably declines.

Why is my Brother printer connected but offline?

This usually occurs because of network interruptions, incorrect printer settings, or communication problems between the computer and printer.

Can third-party toner cartridges cause errors?

Yes. Some third-party cartridges may trigger toner detection or print quality issues. Brother notes that genuine consumables are designed for optimal compatibility.

Conclusion

Following this Brother MFC-L3770CDW troubleshooting guide can help you resolve the most common printing, scanning, networking, paper feed, toner, and drum problems without professional assistance. By keeping your drivers and firmware updated, performing regular maintenance, and addressing small issues early, you can improve print quality, reduce downtime, and extend the lifespan of your Brother MFC-L3770CDW printer.