Скорее всего у девайсов разные country code. Для разных стран доступны разные каналы.
Я на своем роутере посто сменил country code:
$ ssh 192.168.0.1
ASUSWRT RT-AC66U_3.0.0.4 Tue Sep 25 02:42:17 UTC 2012
root@(none):/tmp/home/root# nvram show | grep -E 'ccode|regrev|regulation|wl[0-9]_country|wl[0-9]_reg_mode' | sort
size: 38607 bytes (26929 left)
pci/1/1/ccode=EU
pci/1/1/regrev=15
pci/2/1/ccode=EU
pci/2/1/regrev=15
regulation_domain=EU
regulation_domain_5G=EU
wl0_country_code=EU
wl0_country_rev=15
wl0_reg_mode=off
wl1_country_code=EU
wl1_country_rev=15
wl1_reg_mode=off
root@(none):/tmp/home/root# nvram set pci/1/1/ccode=CN
root@(none):/tmp/home/root# nvram set pci/1/1/regrev=5
root@(none):/tmp/home/root# nvram set pci/2/1/ccode=CN
root@(none):/tmp/home/root# nvram set pci/2/1/regrev=5
root@(none):/tmp/home/root# nvram set regulation_domain=CN
root@(none):/tmp/home/root# nvram set regulation_domain_5G=CN
root@(none):/tmp/home/root# nvram set wl0_country_code=CN
root@(none):/tmp/home/root# nvram set wl0_country_rev=5
root@(none):/tmp/home/root# nvram set wl1_country_code=CN
root@(none):/tmp/home/root# nvram set wl1_country_rev=5
root@(none):/tmp/home/root# nvram show | grep -E 'ccode|regrev|regulation|wl[0-9]_country|wl[0-9]_reg_mode' | sort
size: 38599 bytes (26937 left)
pci/1/1/ccode=CN
pci/1/1/regrev=5
pci/2/1/ccode=CN
pci/2/1/regrev=5
regulation_domain=CN
regulation_domain_5G=CN
wl0_country_code=CN
wl0_country_rev=5
wl0_reg_mode=off
wl1_country_code=CN
wl1_country_rev=5
wl1_reg_mode=off
root@(none):/tmp/home/root# nvram commit
root@(none):/tmp/home/root# reboot
