It seems VPN is OK, but Google does recommend allowing a specific range to ensure your controller connects properly, " If you use a firewall or VPN, make sure your rules don't restrict traffic on por...
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It seems VPN is OK, but Google does recommend allowing a specific range to ensure your controller connects properly, " If you use a firewall or VPN, make sure your rules don't restrict traffic on ports in the range 44700 - 44899 (TCP and UDP). These ports are required for playing games on Stadia. Please note that this range might change in the future."
Also, I wonder if your Chromecast volume is up. When my game was at low volume but my TV volume was high, I found that the Chromecast volume was low. Turn 'em up!