Your laptop and phone joined the new router immediately. The smart bulb, plug, camera or speaker that worked yesterday now refuses to connect. That does not necessarily mean the new router is defective—or that the old device is dead.
If every current phone and computer connects while only an older IoT device fails, treat that pattern as a compatibility clue. The useful fix is usually a 2.4 GHz, WPA2-compatible IoT network—not rolling the entire household back to older security settings.
Why Wi-Fi 7 exposes old smart-device limitations
Wi-Fi 7 is designed to improve capacity, latency and performance for current hardware. The problem is that a inexpensive smart plug may contain a radio and firmware stack designed years before Wi-Fi 7 or WPA3 existed. It does not need Wi-Fi 7 speed, but it still has to authenticate correctly and complete setup through a modern phone app.
ASUS specifically documents that some older IoT devices cannot authenticate with WPA3 and recommends a dedicated WPA2 IoT network on compatible Wi-Fi 7 routers. Google likewise notes that some smart-home devices use only 2.4 GHz and may require the setup phone to be on that same band.
The four most common causes
| What changed | What you may see | Best first move |
|---|---|---|
| 2.4 and 5 GHz share one name | The app cannot discover or complete setup for a 2.4 GHz-only device. | Temporarily use a dedicated 2.4 GHz or IoT network. |
| WPA3 or transition mode | The correct password is repeatedly rejected. | Use WPA2-Personal on the dedicated IoT network. |
| Guest or AP isolation | The device joins Wi-Fi but the phone cannot find it. | Keep the phone and device on a network that permits local discovery during setup. |
| Old network details remain stored | The device keeps trying the former router or stalls during pairing. | Reset only the device’s network setup and add it again. |
Use this troubleshooting order
- Confirm that the router’s 2.4 GHz radio is enabled. Do not assume a single visible Wi-Fi name means every setup app will handle band selection correctly.
- Create a temporary or permanent IoT network. Use 2.4 GHz and WPA2-Personal if the device manufacturer does not document WPA3 support.
- Connect the setup phone to that network. Bluetooth may initiate pairing, but local Wi-Fi discovery often completes it.
- Disable client isolation during setup. A guest network can intentionally prevent the phone and smart device from seeing each other.
- Reset and re-add the individual device. Avoid resetting the entire router when one legacy accessory is the only failure.
The details worth writing down
Before contacting the device maker or FlashRouters support, record the exact device model, whether it can see the network, whether the password is rejected, and whether setup fails before or after it joins Wi-Fi. Those four details separate a radio-band problem from authentication or local-network discovery far faster than “it won’t connect.”
Should you separate the bands permanently?
Not always. Band steering is convenient for modern devices because the router can choose between 2.4, 5 and 6 GHz. A separate 2.4 GHz name is most useful when the smart device’s onboarding software is fragile, when you need a WPA2-only compatibility zone, or when you want clearer separation between older IoT products and personal computers.
If you use an ASUS model, the ASUSWRT setup guide provides the relevant Wi-Fi controls. The Asuswrt-Merlin guide also covers separating 2.4 and 5 GHz networks on supported models.
When the router upgrade is still worthwhile
One stubborn bulb should not prevent a worthwhile network upgrade. A correctly configured compatibility network can preserve older accessories while the rest of the household gains newer radios, better capacity and modern VPN features. FlashRouters’ current Wi-Fi 7 VPN router collection includes value, tri-band and high-performance options, with configuration support for households that would rather not solve every firmware detail alone.
Choosing Wi-Fi 7 for a device-heavy home?
Compare FlashRouters models by coverage, bands and firmware. If older smart-home gear is part of the move, ask us which options provide the cleanest IoT-network controls before ordering.
A sensible long-term setup
Keep computers and newer phones on the primary WPA2/WPA3 network. Put legacy bulbs, plugs and similar appliances on a dedicated 2.4 GHz IoT network when the router supports it. If a device still requires obsolete encryption or unexplained cloud access, replacement may be safer than weakening the network around it.
That division is not about chasing maximum speed. It gives low-bandwidth devices the compatibility they need and keeps their limitations from dictating settings for the rest of the home.
Sources: ASUS: IoT devices and Wi-Fi 7 compatibility; Google Home: troubleshooting 2.4 GHz setup.