Blame Wi-Fi drivers for printer (mDNS) discovery issues
23 days ago
- #Network Troubleshooting
- #Wi-Fi
- #mDNS
- Printer and Chromecast connections over Wi-Fi are often unreliable due to mDNS discovery issues.
- mDNS (Multicast DNS) is a zero-configuration protocol used by devices like printers, Chromecast, and IoT hardware for auto-discovery.
- mDNS uses multicast UDP packets and does not require centralized management, resolving hostnames to IP addresses within the *.local domain.
- DNS-SD (DNS Service Discovery) extends mDNS by defining service types, such as _ipp._tcp.local for printers.
- Several Wi-Fi driver bugs affect mDNS functionality:
- 1. Intel Wi-Fi cards (AX201, AX210, etc.) fail to process mDNS after suspend-resume cycles (unfixed as of 2025).
- 2. Qualcomm QCA6174 cards in Surface Go tablets exhibit similar issues, unlikely to be fixed due to lack of support.
- 3. Mediatek MT6572M chips mishandle WPA2 encryption for multicast; switching to WPA/WPA2 mixed mode resolves this.
- 4. Ubiquiti Access Points incorrectly use key indices for multicast traffic, fixed in firmware 5.43.34.12682.
- mDNS issues arise because multicast traffic relies on Group Temporal Key (GTK), which is prone to rekeying and driver bugs.
- Multicast over Wi-Fi requires IGMP group joins, but drivers may mishandle these, dropping packets incorrectly.
- VPNs or multihoming can break mDNS if applications route traffic incorrectly.
- Solutions include disabling multicast filtering, using mixed WPA/WPA2 security, disabling GTK rekeying, or creating a dedicated Wi-Fi network for printers.