Some customers report that their printer stops working after installing or enabling Trend Micro Security or Trend Micro VPN.
This post explains why this happens, when it is expected behavior, and how to restore printing safely.
Why Printing Can Stop When Trend Micro Is Enabled
Most printer issues fall into two categories:
- Local network security controls (Firewall / Network Protection)
- VPN‑related network isolation
These are not random bugs—they are usually the result of how operating systems and networks handle security and traffic isolation.
Scenario 1: Printer Blocked by Trend Micro Security (Firewall / Network Protection)
✅ This is expected security behavior, not a product defect
Trend Micro Security monitors local network traffic to prevent:
- Unauthorized device access
- Lateral movement by malware
- Exploits using open network ports
Many printers:
- Use open or legacy ports
- Broadcast via network discovery
- Do not authenticate traffic
Because of this, the firewall may:
- Block printer discovery
- Block print jobs
- Mark the printer as an unknown device
Common Symptoms:
- Printer appears offline
- Printer not detected on the network
- Print jobs get stuck or fail
- Printing works when Trend Micro is disabled
How Users Can Fix It Safely
- Add the printer to the trusted network
- Ensure the network is set to Private / Home
- Avoid using Public network mode
- Allow printer communication
- Add printer IP or application to the Exception / Allowed list
- Allow inbound/outbound local network traffic for the printer
- Temporarily test (for diagnosis only)
- Disable Firewall briefly
- If printing works, re‑enable Firewall and configure exceptions (Do not leave protection disabled)
Scenario 2: Printer Not Working When VPN Is Enabled
⚠️ This is a known VPN limitation, not a Trend Micro bug
When a VPN is active:
- Your device traffic is routed through an encrypted tunnel
- Local network devices (like printers) may become unreachable
This behavior is controlled by the operating system’s VPN framework, not by Trend Micro alone.
Common Symptoms:
- Printer works when VPN is OFF
- Printer disappears when VPN is ON
- Network printer cannot be found
- Wireless printing fails during VPN connection
How Users Can Fix It Safely
- Turn off VPN when printing to a local printer
- Use USB printing instead of network printing
- Enable split tunneling (if available) so local network traffic bypasses VPN
- Use cloud‑based printing features (if supported by the printer)
What Trend Micro Is Doing
- Improving device detection and trust flows
- Reducing false positives for common printer software
- Enhancing VPN handling during network changes
- Updating guidance so customers can configure printers safely
