Automatically Restarting Your WiFi 5GHz Channel on Asus Merlin Routers
Dynamic Frequency Selection (DFS) is a feature used in 5GHz WiFi networks to avoid interference with radar systems. However, this can cause your router to switch to a lower channel.
DFS channels are part of the 5GHz band and are shared with radar systems. When a radar signal is detected, the router must switch to a non-DFS channel to avoid interference. This can lead to a decrease in network performance, especially if the new channel is crowded. 1 2
From personal experience, I've noticed that my Asus router sometimes switches to a non-DFS channel, but very rarely, since I don't live near an airport or a military base and I'm not entirely sure what triggers the switch.
Setting Up Automatic Channel Checking
To automate the process of checking and restarting the WiFi channel, you can use a script that periodically checks if the channel has changed and restarts the WiFi if necessary. Here's how you can set it up:
Step 1: Create the channel-ck.sh Script
First, SSH into your router and navigate to the /jffs/scripts/ directory. Create a new script file named channel-ck.sh:
asus@RT-AX88U_Pro:/tmp/home/root# cd /jffs/scripts/
asus@RT-AX88U_Pro:/jffs/scripts# vi channel-ck.sh
Add the following content to the script:
#!/bin/sh
logger -t "channel_check" "Checking..."
ifname="$(nvram get wl1_ifname)"
targchanspec="$(nvram get wl1_chanspec)"
targchan=${targchanspec%/*}
currchanspec="$(wl -i $ifname chanspec | awk '{print $1}')"
currchan=${currchanspec%/*}
if [ "$targchan" != "0" ] && [ "$currchan" != "$targchan" ]; then
logger -t "channel_check" "Channel has changed from ${targchan} to ${currchan}. Restarting WiFi."
service restart_wireless
fi
logger -t "channel_check" "Done."
Make the script executable:
chmod a+rx /jffs/scripts/channel-ck.sh
Step 2: Schedule the Script with cru
You can use the cru command to schedule the script to run at specific intervals. This can be done by updating the services-start file or directly using the cru command.
Option 1: Update services-start File
Edit the services-start file in the /jffs/scripts/ directory:
asus@RT-AX88U_Pro:/jffs/scripts# vi services-start
Add the following lines to schedule the script:
#!/bin/sh
# Workdays (Monday to Friday) at 20 minutes past every hour from 0-8 AM and 7-11 PM
/usr/sbin/cru a channel_ck_weekdays "20 0-8,19-23 * * 1-5 sh /jffs/scripts/channel-ck.sh"
# Weekends (Saturday and Sunday) at 20 minutes past every hour
/usr/sbin/cru a channel_ck_weekends "20 * * * 6,0 sh /jffs/scripts/channel-ck.sh"
Option 2: Use cru Command Directly
Alternatively, you can use the cru command directly in the terminal to set up the cron jobs:
/usr/sbin/cru a channel_ck_weekdays "20 0-8,19-23 * * 1-5 sh /jffs/scripts/channel-ck.sh"
/usr/sbin/cru a channel_ck_weekends "20 * * * 6,0 sh /jffs/scripts/channel-ck.sh"
End
By setting up this script and scheduling it with cru, you can ensure that your router automatically checks and restarts the WiFi 5GHz if it switches due to DFS. 3 4