Turn off 5ghz networsk on Asus Lyra Voice aiMesh node

[avatauro]

Hi all!
I needed the cheapest aiMesh device to extend my network, so bought an Asus Lyra Voice.
The configuration was a pain, I had many problems when I tried adding it to the aiMesh but in the end I succeded.
My main router is an asus-merlin AC68U, while the Lyra has the stock firmware from Asus.
Everything seems to be working fine, except i'm not using the 5ghz network on my main router, but my Lyra is broadcasting 2 5ghz networks anyway... i tried turning them off manually but i failed.
I found this entries in the nvram:

wl_radio=1

wl0_radio=1
wl0.1_radio=1
wl0.2_radio=1

wl1_radio=1
wl1.1_radio=1
wl1.2_radio=1

wl2_radio=1
wl2.1_radio=1
wl2.2_radio=1
wl2.3_radio=1

I tried doing

nvram set wl1_radio=0
nvram set wl2_radio=0
nvram commit
service restart_wireless

but nothing changed, the 2 5Ghz networks are up and running.
Any suggestions?

Thanks in advance!