Unable to cast across subnets?

Configuration
1

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?

2

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.

3

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

4

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

OR

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

5

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.

6

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