Undervolting AsusWRT/Merlin AC66B1 (Probably the same for the AC68U, AC1900, similar models such as Tenda AC15 & AC18), slight adjustments may be needed for other Asus models, and wifi standards such as Wifi 6/6e/7, and so on.
• Regulatory limits: going below legal limits is fine.
A brief guide to undervolting Asuswrt wifi. Helpful if the user is typically within close proximity to the device, such as in my case (~4 feet) and do not require nearly as much power, wish to reduce radio interference in your environment, reduce surface area for hackers or the public, or to mitigate the health effects of wireless radiation.
The settings below are basically the lowest power one can get while maintaining maximum speed and stability within 5-15 feet of the device; you can use this as a baseline and work up from there if need be.
Overview:
• Choose which RF antenna chains are enabled for transmitting on the specified interface (e.g disable all but one or two antenna for 2.4g)
• Defines the maximum allowed transmit power (dBm) for each antenna in a given band.
• Forces the radio to transmit at specified power level for the specified wireless interface.
In Asuswrt Place in
in Tomato, Under Advanced/Scripts: wan up **main**
Reboot required.
Notes:
wl -i eth1 txchain 1 --> worked for my needs
wl -i eth2 txchain 5 --> 5g needed more than 1 antennae for connection stability with 6mv at 4 feet
wl -i eth1 txpwr1 -o -m 4 <-------- 2.4 g, anything below 4 maxes out TX power resulting in coverage at 120 ft.
wl -i eth2 txpwr1 -o -m 6 <-------- 5g, 4 & 5 breaks 5g connections, below 4 may also max out TX power
Get current power: wl -i eth* txpwr1
Get current chain: wl -i eth* txchain
wl -i eth2 txchain # *where # = 1-7 as shown below; pick which TX antennae's you wish to enable (default 7)
1 Chain 0 only Use only antenna chain 0
2 Chain 1 only Use only antenna chain 1
3 (0+1) Chains 0 and 1 Use antenna chains 0 and 1
4 Chain 2 only Use only antenna chain 2
5 (0+2) Chains 0 and 2 Use antenna chains 0 and 2
6 (1+2) Chains 1 and 2 Use antenna chains 1 and 2
7 (0+1+2) Chains 0, 1, and 2 Use all three antenna chains (default)
Looking at the router from the front:
Left antenna = Chain 0
Middle antenna = Chain 1
Right antenna = Chain 2
MaxPower Defaults:
Tomato Tenda AC15 (same as ac66ub1 with less ram/cache)
nvram show | grep maxp
1:maxp5ga0=98,98,98,98
1:maxp5ga1=98,98,98,98
1:maxp5ga2=98,98,98,98
0:maxp2ga0=104
0:maxp2ga1=104
0:maxp2ga2=104
ASUS AC68/66U_B1
nvram show | grep maxp
1:maxp5ga0=52,52,52,52
1:maxp5ga1=52,52,52,52
1:maxp5ga2=52,52,52,52
0:maxp2ga0=52
0:maxp2ga1=52
0:maxp2ga2=52
Going from 52 to 13, how much less RF does this equate to in an environment?
Broadcom stores power in ¼-dB units.
• 52 × 0.25 dB = 13 dBm ≈ 20 mW per chain
• 13 × 0.25 dB = 3.25 dBm ≈ 2 mW per chain
13 dBm – 3.25 dBm = 9.75 dB
9.75 dB ≈ 10× reduction in power.
New settings
2.4 GHz (eth1)
txpwr1 -m 4 dBm ≈ 2.5 mW per chain
txchain 1 = 1 active chain
→ 2.5 mW total (was 60 mW)
Equals 96% reduction in power for 2.4g
5 GHz (eth2)
txpwr1 -m 6 dBm ≈ 4 mW per chain
txchain 5 = 2 active chains (0 + 2)
→ 4 mW × 2 = 8 mW total (was 60 mW)
Equals 87% reduction in power for 5g
• Regulatory limits: going below legal limits is fine.
A brief guide to undervolting Asuswrt wifi. Helpful if the user is typically within close proximity to the device, such as in my case (~4 feet) and do not require nearly as much power, wish to reduce radio interference in your environment, reduce surface area for hackers or the public, or to mitigate the health effects of wireless radiation.
The settings below are basically the lowest power one can get while maintaining maximum speed and stability within 5-15 feet of the device; you can use this as a baseline and work up from there if need be.
Overview:
Code:
wl -i eth1 txchain #
Code:
nvram set 1:maxp5ga0/0:maxp2ga0
Code:
wl -i eth1/eth2 txpwr1 -o -m 4/6In Asuswrt Place in
Code:
/jffs/scripts/services-start
Code:
wl -i eth1 txchain 1
wl -i eth2 txchain 5
wl -i eth1 txpwr1 -o -m 4
wl -i eth2 txpwr1 -o -m 6
nvram set 1:maxp5ga0=13,13,13,13
nvram set 1:maxp5ga1=13,13,13,13
nvram set 1:maxp5ga2=13,13,13,13
nvram set 0:maxp2ga0=13
nvram set 0:maxp2ga1=13
nvram set 0:maxp2ga2=13Reboot required.
Notes:
wl -i eth1 txchain 1 --> worked for my needs
wl -i eth2 txchain 5 --> 5g needed more than 1 antennae for connection stability with 6mv at 4 feet
wl -i eth1 txpwr1 -o -m 4 <-------- 2.4 g, anything below 4 maxes out TX power resulting in coverage at 120 ft.
wl -i eth2 txpwr1 -o -m 6 <-------- 5g, 4 & 5 breaks 5g connections, below 4 may also max out TX power
Get current power: wl -i eth* txpwr1
Get current chain: wl -i eth* txchain
wl -i eth2 txchain # *where # = 1-7 as shown below; pick which TX antennae's you wish to enable (default 7)
1 Chain 0 only Use only antenna chain 0
2 Chain 1 only Use only antenna chain 1
3 (0+1) Chains 0 and 1 Use antenna chains 0 and 1
4 Chain 2 only Use only antenna chain 2
5 (0+2) Chains 0 and 2 Use antenna chains 0 and 2
6 (1+2) Chains 1 and 2 Use antenna chains 1 and 2
7 (0+1+2) Chains 0, 1, and 2 Use all three antenna chains (default)
Looking at the router from the front:
Left antenna = Chain 0
Middle antenna = Chain 1
Right antenna = Chain 2
MaxPower Defaults:
Tomato Tenda AC15 (same as ac66ub1 with less ram/cache)
nvram show | grep maxp
1:maxp5ga0=98,98,98,98
1:maxp5ga1=98,98,98,98
1:maxp5ga2=98,98,98,98
0:maxp2ga0=104
0:maxp2ga1=104
0:maxp2ga2=104
ASUS AC68/66U_B1
nvram show | grep maxp
1:maxp5ga0=52,52,52,52
1:maxp5ga1=52,52,52,52
1:maxp5ga2=52,52,52,52
0:maxp2ga0=52
0:maxp2ga1=52
0:maxp2ga2=52
Going from 52 to 13, how much less RF does this equate to in an environment?
Broadcom stores power in ¼-dB units.
• 52 × 0.25 dB = 13 dBm ≈ 20 mW per chain
• 13 × 0.25 dB = 3.25 dBm ≈ 2 mW per chain
13 dBm – 3.25 dBm = 9.75 dB
9.75 dB ≈ 10× reduction in power.
New settings
2.4 GHz (eth1)
txpwr1 -m 4 dBm ≈ 2.5 mW per chain
txchain 1 = 1 active chain
→ 2.5 mW total (was 60 mW)
Equals 96% reduction in power for 2.4g
5 GHz (eth2)
txpwr1 -m 6 dBm ≈ 4 mW per chain
txchain 5 = 2 active chains (0 + 2)
→ 4 mW × 2 = 8 mW total (was 60 mW)
Equals 87% reduction in power for 5g
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