Unable to cast across subnets?

I have a Google Nest Hub Max sitting on my desk which I got as a freebie and don’t use much. I was using it to simply cast a dashboard to it for convenience. I am now unable to cast to it at all.

Specifically, what exact protocols and ports are needed to allow between the devices, to cast from a chrome tab on a PC showing an HA dashboard to a Google Nest Hub Max that is running on a different subnet?

All the devices have static IP addresses. Maybe there is a way to expose the Google Nest Hub Max across the other subnet to fix the issue?

I think Google Cast, and many other casting services, use broadcast packets, so you need to set up helpers/forwarders on your router for that traffic.

Thank you yes I’ll do some checking, just thought someone here would know!

It’s not port issue, it is protocol.

Why not place it in same vlan/subnet? You can use firewall rules to limit access if needed


Can’t the nest hub max show webpages? Why not just use that?

I use Chromecast across VLANs between my internet network and IoT network (where the chromecasts are) for my Chromecast, Google TV’s and Smart Speakers/Displays.

For discovery they use multicast dns (mdns), which I needed to setup a repeater.

I also have a firewall between the IoT and the internal VLANs so needed to open ports for each application. E.g. VLC I added port 8010, and to display the HA dash, I needed to open 8123.

Figured it out -

Configured the network to allow mDNS as well as IGMP (Internet Group Management Protocol)
I ensured the following ports are open between the subnets:
TCP Ports: 8008, 8009 (used by Google Cast devices for communication and control)
UDP Ports: 1900 (used for SSDP, Simple Service Discovery Protocol), 5353 (used for mDNS, multicast DNS)

Tanks everyone for their help