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.

Recommended Wi-Fi Settings¶

5GHz Settings¶

Recommended Configuration¶

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¶

Recommended Configuration (2.4 GHz)¶

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.