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ASUS RT-AX57 Wi-Fi Stability Settings

Background

I use FortiClient VPN for work. Before tuning the Wi-Fi settings, the VPN sometimes disconnected unexpectedly.

Symptoms:

  • ping 1.1.1.1 sometimes jumped to 80–130ms+
  • ping 192.168.50.1 also showed latency spikes
  • FortiClient VPN occasionally disconnected
  • Wired Ethernet was very stable

This means the issue was most likely in the local Wi-Fi link, not the ISP, WAN connection, or public Internet route.

The goal of this setup is not to maximize theoretical Wi-Fi speed, but to improve latency stability and reduce jitter.

Key Findings

Wired Ethernet Was Stable

When testing with Ethernet, latency was very stable:

min/avg/max/stddev = 4.214/5.139/13.876/1.880 ms

This suggested that the ISP, WAN connection, and router routing performance were not the main problem.

Wi-Fi Had Local Latency Spikes

Even when pinging the router directly:

ping 192.168.50.1

there were latency spikes. This confirmed that the issue was inside the local Wi-Fi link.

After Tuning

After changing the 5GHz settings to a more conservative and stable configuration, the result became much better:

min/avg/max/stddev = 6.259/9.205/11.581/1.979 ms

FortiClient VPN stability also improved noticeably.

5GHz Settings

:::{list-table} 5 GHz recommended Wi-Fi configuration :header-rows: 1 :name: wifi-5ghz-config * - Item - Setting * - Smart Connect - OFF * - Band - 5GHz * - Wireless Mode - N/AC/AX mixed * - 802.11ax / Wi-Fi 6 mode - Enabled * - WiFi Agile Multiband - Disabled * - Target Wake Time - Disabled * - Channel Bandwidth - 80 MHz * - Enable 160 MHz - OFF * - Channel - Fixed 36 * - Extension Channel - Auto * - Authentication Method - WPA2/WPA3-Personal * - WPA Encryption - AES :::

5GHz Notes

1. Avoid Auto Wireless Mode

When Wireless Mode was set to Auto, Wi-Fi latency spikes were noticeable.

After changing it to:

N/AC/AX mixed

the connection became much more stable.

Before tuning:

max 90–130ms+
stddev 20–30ms+

After tuning:

max around 10–12ms
stddev around 2ms

2. Avoid DFS Channels

The previous 5GHz channel was:

Channel: DFS, 100

DFS channels may require the router to avoid radar signals. This can cause:

  • temporary transmission pauses
  • background scanning
  • channel switching
  • latency spikes
  • VPN instability

Use a fixed non-DFS channel instead:

Channel 36

Other possible non-DFS options:

36 / 40 / 44 / 48

3. Disable 160MHz

The previous setting used:

5GHz, 160MHz

Although 160MHz can provide a higher theoretical link rate, it is more sensitive to interference and DFS-related issues.

For stability, use:

80MHz

and disable:

Enable 160 MHz

4. Use 5GHz for Main Devices

Use the 5GHz SSID for devices that need stable connectivity:

  • Mac
  • Windows PC
  • smartphones
  • tablets
  • work devices
  • VPN devices
  • video meeting devices
  • remote desktop devices
  • gaming devices

For important meetings, remote desktop, or long VPN sessions, wired Ethernet is still the best option when available.

2.4GHz Settings

:::{list-table} 2.4 GHz recommended Wi-Fi configuration :header-rows: 1 :name: wifi-2ghz-config * - Item - Setting * - Smart Connect - OFF * - Band - 2.4GHz * - Wireless Mode - N only or Auto * - Channel Bandwidth - 20 MHz * - Channel - Fixed 1, 6, or 11 * - Authentication Method - WPA2/WPA3-Personal * - WPA Encryption - AES :::

2.4GHz Notes

1. Use 20MHz Channel Bandwidth

For 2.4GHz, use:

20MHz

Avoid:

40MHz

The 2.4GHz band is usually crowded, especially in apartments.

Using 40MHz can increase:

  • interference
  • retransmissions
  • jitter
  • latency spikes

For stability, 20MHz is usually better.

2. Use a Fixed Channel

For 2.4GHz, use one of these channels:

1 / 6 / 11

Avoid Auto if you want predictable behavior.

If there are many nearby Wi-Fi networks, use a Wi-Fi analyzer and choose the least congested one among 1, 6, and 11.

3. Use 2.4GHz Mainly for IoT and Legacy Devices

Use 2.4GHz mainly for:

  • smart home devices
  • printers
  • robot vacuums
  • old phones
  • old tablets
  • devices that only support 2.4GHz

Avoid using 2.4GHz for:

  • work laptops
  • VPN
  • video meetings
  • remote desktop
  • gaming
  • latency-sensitive applications

Final Configuration Summary

5GHz

Smart Connect: OFF
Wireless Mode: N/AC/AX mixed
Wi-Fi 6 Mode: Enabled
Channel Bandwidth: 80MHz
Enable 160MHz: OFF
Channel: 36
DFS: Avoid
Main usage: work devices / VPN / meetings / main devices

2.4GHz

Smart Connect: OFF
Wireless Mode: N only or Auto
Channel Bandwidth: 20MHz
Channel: 1 / 6 / 11
Main usage: IoT / legacy devices only

Test Commands

Test Public Internet Latency

ping 1.1.1.1

This tests the path from the local device to the public Internet.

Test Local Wi-Fi Latency to the Router

ping 192.168.50.1

This tests only the local Wi-Fi link between the device and the router.

If ping 192.168.50.1 has latency spikes, the issue is likely in the local Wi-Fi link, not the ISP or public Internet route.

Before and After

Before

Wi-Fi often had spikes like:

time=80ms
time=95ms
time=112ms
time=135ms

The standard deviation was high:

stddev 20ms–30ms+

FortiClient VPN sometimes disconnected unexpectedly.

After

After using:

Fixed non-DFS 5GHz channel
80MHz bandwidth
160MHz disabled
N/AC/AX mixed Wireless Mode
Smart Connect disabled

the Wi-Fi became much more stable:

min/avg/max/stddev = 6.259/9.205/11.581/1.979 ms

FortiClient VPN stability improved noticeably.

Conclusion

ASUS router default Auto settings tend to prioritize theoretical speed and compatibility, but they are not always ideal for low-latency and VPN-stability scenarios.

For daily work and VPN usage, stability-oriented settings are better:

Use a fixed non-DFS channel
Use 80MHz
Disable 160MHz
Use N/AC/AX mixed Wireless Mode
Disable Smart Connect
Use 2.4GHz only for IoT or legacy devices

This conservative setup may reduce the theoretical link rate, but it provides much better real-world stability.