Ports used by HP Smart (Android) to discovery the printer

[mhalano]

I have two separated networks, one for my IoT devices, like the printer, and the main network for my devices, like computer and smartphone.

I enabled mDNS between the two networks, and my printer works from my computer.

Also works when I add the IP on my smartphone.

But if I try to discover from HP Smart app, it doesn't detect.

The communication from the main network to the IoT network, is full, but the IoT network has just a few privileges to start communication with my main network, one of them is mDNS.

Besides mDNS, there is other port that I need to open so the printer, that is in my IoT network, can actively send data to my main network? Existent connections, since started by the main network, are kept.

[Max3Aj]

@mhalano, Welcome to HP Support Community. 

Thank you for posting your query, I will be glad to help you. 
To help you resolve the issue with HP Smart (Android) not discovering your HP Ink Tank Wireless 410 series printer across segmented networks, here’s a detailed explanation and steps to ensure proper communication:

Understanding the Discovery Mechanism

The HP Smart app uses several protocols and ports for printer discovery and communication:

1. mDNS (Multicast DNS) – UDP port 5353
2. SSDP (Simple Service Discovery Protocol) – UDP port 1900
3. SNMP (Simple Network Management Protocol) – UDP port 161
4. HTTP/HTTPS – TCP ports 80 and 443
5. IPP (Internet Printing Protocol) – TCP port 631
6. HP Web Services – TCP port 5222 (for cloud printing and remote access)

Since you’ve already enabled mDNS and confirmed that direct IP printing works, the issue likely lies in additional discovery protocols (like SSDP or SNMP) not being allowed from the IoT network to your main network.

Recommended Steps

Ensure the following ports are open from IoT to Main Network:

• UDP 1900 (SSDP)
• UDP 161 (SNMP)
• TCP 80, 443, 631, 5222 (for HTTP, HTTPS, IPP, and HP Web Services)

Enable Location and Bluetooth on Android:

• HP Smart on Android requires Bluetooth and Location Services to be enabled for discovery.
• Ensure the app has Location permission granted.

Use IP Address as a Workaround:

• Since IP-based printing works, you can manually add the printer in HP Smart using its IP:
  • Open HP Smart → Tap Add Printer → Tap Add Printer by IP Address.

Check HP Smart App Requirements:

• Refer to HP’s official setup guide for Android: HP Smart App Setup

Firewall or Router Settings:

• Ensure your router/firewall allows multicast and broadcast traffic between VLANs or subnets.
• Some routers block SSDP or SNMP across VLANs by default.

Additional Tips

• If your router supports Bonjour forwarding or mDNS reflector, ensure it's enabled.
• Consider using HP Print Service Plugin as an alternative for Android: HP printer setup (Print Service Plugin for Android) | undefined

I hope this helps. 

Take care and have a good day. 

Please click “Accepted Solution” if you feel my post solved your issue, it will help others find the solution. Select "Yes" on the bottom left to say “Thanks” for helping! 

Max3Aj

HP Support 

[mhalano]

Thanks. I will work on this during the weekend and I let you know. I configured an mDNS reflector for now. I will check how I can redirect SSDP packages between networks.

[mhalano]

I found the problem, at least about the discovery: the printer uses the source port 5353 to communicate with my mDNS server (Avahi), so I must allow communication from the iot network to reach the router (where Avahi is).

I'm wondering how can I make more secure without limiting the IP to just the one from the printer.

[mhalano]

Answering my own question, Avahi has an ephemeral high port that the printer talks with. I couldn't find an easy way to allow just this port. Technically is possible using a script that finds what the port is being used and adds to the firewall rules, but that's to complicated. What I did was allowing all ephemeral ports for UDP from port 5353. Not the ideal, though. If the printer could talk with the multicast IP address, 244.0.0.251, instead of directly with the router, that would be better.