Frequently Asked Question
Why can I use my printer or smart device on its own VLAN, but cannot find it from another UniFi network?
ACE SUPPORT · UBIQUITI
Cross-VLAN discovery and permission to use a service are separate checks. Confirm both, while keeping the intended separation between trusted devices, guests and IoT equipment.
Applies to
UniFi networks with a UniFi Gateway, including UCG-Fiber, where a printer, AirPlay/Chromecast device or other mDNS service sits on a different VLAN from the client. Not every discovery protocol uses mDNS.
Before you begin
Do not disable all firewall rules, guest isolation or network separation to make one printer appear. Limit any exception to the required trusted client, device and service.
Record current network and rule settings first. Use a test client you control; avoid moving guests into a trusted business network.
Work through these checks
- Test the service with a client on the same VLAN as the device. Confirm normal operation, its current address and the manufacturer's supported discovery method. If this local test fails, fix the device or local wireless problem before changing inter-VLAN settings.
- Confirm that the client and device are on the VLANs you intended. Check the SSID-to-network assignment and DHCP addresses. A similarly named Wi-Fi network or an old saved connection can lead to a misleading comparison.
- In UniFi Network > Settings > Networks, inspect the gateway mDNS settings for the relevant networks. Ubiquiti documents mDNS forwarding for discovery between selected VLANs, with Auto using a predefined service list and Custom allowing selected services.
- If the required service is absent from Auto, use the device manufacturer's service information to choose the relevant Custom entry. Scope discovery to the necessary networks; there is no need to publish every service to guests.
- Review routing and firewall/ACL policy separately. Discovery can make an icon appear while the actual print, audio or control connection remains blocked. Ask the network administrator to permit only the required service and return traffic, then repeat the real task.
Confirm the result
From the intended trusted VLAN, rediscover the device and complete a test print, playback or control action. Confirm that guest access and other isolation still behave as designed.
When to contact us
Give our Support Specialist a redacted topology, both network ranges, service model, mDNS mode and same-VLAN versus cross-VLAN results. Do not post device addresses, rule exports or customer network details publicly.
Related ACE guides
Updated 261105