Chromecast is not working with iPhone When I connect certain AP 5GHz

Dear apple team,

I am an WiFi engineer of LG Electronics commercial TV.

We have a field issue about iPhone and Chroemcast with our product.

I think iPhone block local network communication when WiFi is connected LG commercial TV SoftAP 5GHz.

(This issue only happen with SoftAP 5GHz. It is no problem in SoftAP 2.4GHz.)

In this case iPhone does not send ARP response about ARP request of Chromecast.

It cause Chromecast is not working even if wifi is connected successfully both Chromecast and iPhone.

I refer to follow link and enable local network google home.

Chromecast not working after ios14 update - Apple Community

However It is still not working.

I wonder what condition does iPhone block local network communication in case of connecting 5GHz SoftAP.

Thank you.