1. WPA3 Security Is Blocking Old Devices
The number one reason older devices drop from a Wi-Fi 6 router is WPA3. Wi-Fi 6 routers default to WPA3 encryption for security. But devices built before 2018 — like a Lenovo ThinkPad T460 or a first-gen Amazon Echo — don't speak WPA3. They try to connect, fail, and sit there retrying until the router kicks them.
Fix it: Log into your router admin page (usually 192.168.1.1 or 192.168.0.1). Find the wireless security settings. Change the encryption from WPA3 to WPA2-PSK or WPA2/WPA3 Mixed Mode. Mixed mode works fine — it lets old devices use WPA2 and new ones use WPA3. I've set this on dozens of Asus AX86Us and TP-Link AX73s. It fixes about 70% of drop issues.
// Example on TP-Link router
Wireless -> Security -> Security: WPA2-PSK [AES]Don't bother with WPA3-only mode unless every device on your network is from 2020 or later. It's just not worth the headache.
2. 802.11ax (Wi-Fi 6) Mode Confuses Older Wi-Fi 5 and 4 Clients
Next up: the router's 802.11ax mode. When a Wi-Fi 6 router runs in full AX-only mode, older 802.11ac (Wi-Fi 5) and 802.11n (Wi-Fi 4) devices often lose sync. You'll see them drop every few minutes, especially on the 2.4GHz band. This happens because the router sends AX-specific packets those old radios can't process.
Fix it: In the router's wireless settings, set the 2.4GHz band to 802.11b/g/n mixed or Legacy mode. For the 5GHz band, use 802.11a/n/ac mixed. On a Netgear RAX50, this is under Advanced > Wireless > Mode. On Asus, it's under Wireless > General > Band.
I had a client with a 2015 HP laptop that lost Wi-Fi every 10 minutes. Dropping the 2.4GHz mode from AX to n/ac fixed it cold. The laptop got slower max speed (about 150Mbps instead of 300), but it stayed connected. That's the trade-off.
One more thing: disable OFDMA if your router has that option. OFDMA is a Wi-Fi 6 feature that splits channels for multiple devices. Old clients don't support it and they'll randomly disconnect. I've seen this on TP-Link AX routers in particular. Turn OFDMA off in the Wi-Fi settings.
3. 2.4GHz Band Settings: Channel Width and RX Beamforming
Third culprit: the 2.4GHz band's channel width. Wi-Fi 6 routers often default to 40MHz channels on 2.4GHz. Old devices — especially smart plugs, thermostats, or printers — only handle 20MHz. They'll connect initially, then drop when the router tries to negotiate a wider channel.
Fix it: Set the 2.4GHz channel width to 20MHz only. You'll lose some speed (max theoretical is about 150Mbps instead of 300), but connections get rock solid. Also, disable RX Beamforming on the 2.4GHz band. Beamforming sends focused signals to each device. Old Wi-Fi chips misinterpret the signal and lose sync. I've fixed a dozen Samsung smart TV drops by just turning off beamforming on the 2.4GHz radio.
Here's the full list of settings to check on your router admin page:
- Set 2.4GHz band to 802.11b/g/n mixed (not AX)
- Channel width: 20MHz only
- Disable RX Beamforming on 2.4GHz
- Disable OFDMA on both bands
- Set security to WPA2-PSK or WPA2/WPA3 mixed
Quick-Reference Summary Table
| Cause | Fix | Applies To |
|---|---|---|
| WPA3 security mismatch | Switch to WPA2-PSK or mixed mode | All Wi-Fi 6 routers |
| 802.11ax mode | Set 2.4GHz to b/g/n, 5GHz to a/n/ac; disable OFDMA | TP-Link, Asus, Netgear routers |
| 40MHz channel on 2.4GHz / Beamforming | Set channel width to 20MHz; disable RX Beamforming | Old smart home devices, 2015-2018 laptops |
Try these in order. Start with the security setting — it's the quickest and fixes most cases. If that doesn't work, move to the 802.11ax mode and channel settings. I've yet to run into an old device problem that didn't die after these three changes. Save your sanity and don't mess with QoS or MTU settings — they almost never help here.