Why Cast Devices Aren't Discovered
Google Cast uses mDNS (multicast DNS) to announce devices on the local network. Your PC discovers Cast devices by listening for these announcements on the same network segment. When this doesn't work, the cause is almost always one of these:
- PC and Nest are on different network segments (e.g., 5GHz vs 2.4GHz subnets, or guest network)
- Windows Firewall blocking mDNS traffic (UDP port 5353)
- VPN software suppressing multicast traffic
- Network isolation enabled on your router (AP isolation)
- Nest speaker needs a restart
Step-by-Step Fix
Check they're on the same network
On your PC, open a command prompt and run ipconfig. Look at your IPv4 address — it should start with the same subnet as your Nest (e.g., both 192.168.1.x).
In the Google Home app, check which Wi-Fi network your Nest is connected to. If your PC is on 5GHz and the Nest is on 2.4GHz, they should still be on the same subnet — most modern routers bridge them. If you're using a guest network for the Nest (or vice versa), that's the problem — move both to the same network.
Disable VPN (if running)
Most VPN clients intercept all network traffic, including mDNS multicast packets. Disconnect your VPN entirely and try discovery again. If your Nest shows up, the VPN is the cause — you'll need to configure split-tunneling or disable the VPN when you want to use your Nest as a PC speaker.
Check Windows Firewall
Windows Firewall can block mDNS discovery. To test this, temporarily disable Windows Firewall and try discovering your Nest again.
Settings → Privacy & Security → Windows Security → Firewall & network protection → turn off for Private network. If your Nest appears now, you need to add a firewall exception for mDNS (UDP port 5353) rather than leaving the firewall off.
Check router AP isolation
Some routers have “AP isolation” or “client isolation” enabled, which prevents devices on the same Wi-Fi from communicating with each other. Log into your router admin panel and check wireless settings. Disable AP isolation if enabled.
Restart the Nest speaker
Unplug the Nest speaker for 10 seconds and plug it back in. Wait 60 seconds for it to fully boot and reconnect to Wi-Fi. Cast devices occasionally need a restart to re-announce themselves on the network.
Restart PC Nest Speaker
Close and reopen PC Nest Speaker — the discovery scan runs on startup. If your Nest recently rejoined the network after a reboot, the app may have scanned before the speaker announced itself.
Still Not Working?
If none of the above fixes it, the next step is checking whether your router supports mDNS forwarding across VLANs (if you have a more complex home network setup) or whether a third-party firewall (antivirus, corporate endpoint software) is intercepting multicast traffic.
Contact us at me@pcnestspeaker.app with your network setup details and we'll help diagnose it.
FAQ
My Nest shows in the Google Home app but not in PC Nest Speaker
The Google Home app uses cloud-based device lookup, not local mDNS. It will show your Nest even when local discovery is blocked. PC Nest Speaker needs local network access — the fixes above address this.
It used to work but stopped
Most common causes: a router firmware update that enabled AP isolation, a new VPN client installed, Windows Update that tightened firewall rules, or the Nest speaker moved to a different network.
Can I add devices manually?
PC Nest Speaker currently uses automatic discovery. If auto-discovery fails, work through the network troubleshooting steps above rather than trying to add devices manually.
I'm on a corporate network
Corporate networks frequently block multicast traffic and have managed firewall rules. You may need IT department approval to allow mDNS (UDP 5353) from your PC to the local subnet.
Need help? Contact us directly
If you're stuck, email us at me@pcnestspeaker.app with your network setup and we'll walk you through it.
Contact Support