A router firmware update can genuinely be the cause when several smart home devices go offline right after it installs, but it’s just as often the fix for a problem that already existed, which makes “was it the update?” harder to answer honestly than most troubleshooting guides admit. The most common documented cause, when an update genuinely is responsible, is a change to default security settings, particularly a router defaulting to WPA3 or a mixed WPA2/WPA3 mode after an update, which some older IoT hardware cannot negotiate. The way to tell which situation applies is to check what actually changed in that update’s release notes against the specific symptom, rather than assuming firmware is guilty just because the timing lines up. Router firmware behavior is genuinely vendor-specific and version-specific, so this article names what one major vendor documents rather than generalizing across all routers.
Why WPA3 defaults are the most common documented cause
ASUS’s own support documentation, in a published FAQ addressing exactly this scenario for its Wi-Fi 7 router line (accessed 2026-08-11), states that some IoT devices are unable to connect once a router defaults to WPA3 encryption, because those devices were designed before WPA3 was widely supported and lack the firmware or hardware to negotiate it. The same documentation notes that a mixed WPA2/WPA3-Personal setting, sometimes called transition or compatibility mode, can itself cause connection problems for some IoT devices, and that switching specifically to a WPA2-Personal-only setting is the fix ASUS documents for affected devices. This general WPA3 compatibility mechanism is the same one worth checking any time a security-mode change, firmware-driven or manual, coincides with devices going quiet. This is stated here as one named vendor’s own current documentation, not as universal router behavior, a different manufacturer’s firmware may default differently, and the same manufacturer’s own defaults can change in a future firmware release.
Firmware updates fix things at least as often as they break them
This is the part worth stating honestly rather than treating every post-update problem as the update’s fault. Firmware updates commonly patch known bugs, including specific IoT compatibility issues from earlier firmware versions, adjust band-steering or mixed-mode security behavior that was previously causing problems, and close security vulnerabilities that have nothing to do with smart home compatibility at all. A device that was already having trouble before an update, and continues to have trouble after, is more likely suffering from something unrelated to the update than from the update itself, even if the timing looks suspicious in hindsight.
How to actually check, instead of guessing
The router’s own admin interface generally shows the current firmware version and, for most manufacturers, a changelog or release notes for that specific version, either directly in the interface or linked to the manufacturer’s support site. Reading that changelog for the specific version installed, rather than assuming based on general reputation, is the only way to confirm whether a security-setting default, a DHCP behavior change, or something else genuinely changed in that release. If the release notes mention security mode defaults, DHCP lease behavior, or wireless mode changes, that’s a specific, checkable reason to suspect the update; if the changelog only lists unrelated bug fixes, the timing is more likely a coincidence than a cause.
What to do if the update genuinely is the cause
Where a specific setting change, most commonly a security mode default, is identified as the cause, the fix is usually adjusting that one setting back, such as switching from a mixed WPA2/WPA3 mode to WPA2-only for the affected devices’ network, as ASUS’s documentation describes for its own hardware. Rolling back to a previous firmware version is technically possible on some routers but is generally discouraged by manufacturers, since it can reintroduce the security issues the update was meant to fix; changing the specific setting that’s actually causing the incompatibility is the more targeted and generally safer approach.
What this does not cover
This article covers firmware-driven changes to default settings as a cause of smart home connectivity loss; it does not cover a device that has never connected in the first place, which is a setup problem rather than a firmware regression, and it does not cover interference or signal-strength issues, which are separate diagnoses unrelated to firmware. If several devices dropped at the same time with no known firmware update, the four-way diagnostic is the better starting point than assuming a silent update occurred.
FAQ
How do I know if my router updated its firmware automatically?
Most routers log recent firmware changes in the admin interface, often under a system or firmware status page; some ISP-supplied routers update silently and don’t always surface a clear notification, which is worth checking specifically if the timing of a problem is uncertain.
Should I disable automatic firmware updates on my router?
That’s a tradeoff between convenience and predictability the reader has to weigh; disabling automatic updates means security patches also wait for a manual update, which carries its own risk.
Does every router default to WPA3 after an update?
No; this varies by manufacturer and router model, and ASUS’s own documentation is cited here specifically because it’s the vendor that publishes this behavior clearly, not because every router behaves the same way.
Can I prevent this from happening again?
Checking a router’s release notes before or shortly after each firmware update, rather than only after something breaks, is the most reliable way to catch a settings-default change before it causes a problem.
Is it safer to never update router firmware at all?
Generally no; firmware updates frequently patch real security vulnerabilities, and skipping updates indefinitely carries its own risk that most manufacturer guidance weighs as worse than the occasional compatibility hiccup.
Sources referenced in this article
- ASUS Official Support, [Wireless Router] IoT devices can’t connect to WiFi 7 (BE) router’s WiFi signal? (FAQ 1054763, accessed 2026-08-11). Source for the WPA3-default and mixed-mode compatibility issue and ASUS’s documented WPA2-Personal fix, stated as this vendor’s own current documentation.
A note on freshness: router firmware behavior is vendor- and version-specific and changes over time. The vendor documentation cited above reflects what was published as of 2026-08-11; a reader should check their own router manufacturer’s current documentation rather than assume identical behavior across brands or future firmware versions.
Review interval: 12 months, or immediately if a major router vendor changes documented default security behavior.