So recently I have been having issues with my Discord app on Mac. My phone app worked fine, but the Mac app was constantly crashing on loading and failing to update with a really obscure QUIC_PROTOCOL_ERROR and Google searching wasn’t turning up any results for a fix. All results referred to Google chrome itself, but not third party applications using QUIC. No matter what I tried nothing was working.

After digging into QUIC and how it relates to UDP network packets, (faster handshaking for Web 2.0 applications) I went into my router (DrayTek) firewall settings and I had something called ‘UDP flood defense’ enabled. I disabled this, and immediately my broken discord app started working.

On the router settings page it has the advisory text ‘enabling UDP flood defense option may affect UDP services like NAT-T VPN, DNS, VoIP. Well I’ve just proved it definitely affects QUIC!

The reason I’m posting this related to Sonos, as Sonos is going down the cloud Web 2.0 infrastructure route with speakers talking to Sonos’ central server, it is highly likely it is using QUIC under the hood and if it is, users may find problems go away if they dig in to issues as they relate to QUIC / UDP networking as described.