[Update: Google’s rolling out a fix] Here’s Why Many Google Home and Chromecast Devices are Causing Network Issues
If you started experiencing Wi-Fi connectivity issues around the time you picked up a Google Chromecast or Google Home speaker, you’re not alone. As recently detailed by engineers at TP-Link, there’s a potential corollary between Google’s “Cast” protocol and the instability of wireless networks over which it’s used.
Along with new beta firmware for the TP-Link Archer C1200 router (hardware versions 1, 2, and 3), TP-Link engineers published a full explanation of the Google Cast network bug they discovered. Android phones and tablets and Cast-enabled Google apps such as YouTube, Google Play Movies & TV, and Google Photos maintain an active connection to Google Home and Google Chromecast devices via what are called MDNS packets, or “multicast Domain Name Server” packets. MDNS resolves the hostnames of devices (i.e., the network names assigned to those devices) to IP addresses, and is commonly used on local networks that don’t have a DNS server. They’re normally sent every 20 seconds or so, but when some Google Cast-enabled devices go to sleep, they continue to queue new packets to send until woken up and unlocked. This can cause surges of more than 100,000 packets in a short window — the amount of packets sent is directly proportional to the amount of time the device stays asleep. That causes connectivity issues, of course, but can also crash Wi-Fi routers and affect a number of their core services. The only way to fix it is by rebooting the Wi-Fi router.
If you’re suffering from the issue, TP-Link recommends disabling the Cast feature on your Android phone and/or tablet for now. Alternatively, it recommends disconnecting all Cast-enabled devices from your Wi-Fi network until Google issues a fix.
You can check out TP-Link’s breakdown at the source link, along with the beta firmware update for the Archer C1200 that fixes the issue.