OpenWrt 18.06.2 caused havoc with 5GHz on my Archer C7 v2


#1

I recently upgraded my router TP-Link Archer C7 v2 to Openwrt 18.06.2. Wifi on 5ghz started to have weird issues, like not coming up at all most of the time no matter which channel, mode (legacy, n or ac) or bandwidth (20,40 or 80 Mhz) I chose. Wifi on 5ghz was enabled but would always say "wireless not associated". It came up once or twice, I had a suspicion it has something to do with that radar-evasive behaviour over certain channels, but I tried channels that should be secure from this (like 36 - I am in Europe). Reverting back to LEDE 17.01 fixed the issue. Any ideas what might have been behind it?


#2

Hard to say without seeing your /etc/config/wireless and /etc/config/network (as there are few reported issues with the Archer C7v2 and it is a "mature" port).


#3

Not sure I have anything that unusual:

cat /etc/config/wireless
config wifi-device 'radio0'
        option type 'mac80211'
        option hwmode '11a'
        option path 'pci0000:01/0000:01:00.0'
        option distance '9'
        option legacy_rates '1'
        option country 'CZ'
        option channel '48'
        option htmode 'VHT80'

config wifi-iface 'default_radio0'
        option device 'radio0'
        option mode 'ap'
        option ssid 'supi_hnizdo_5ghz'
        option encryption 'psk2'
        option key 'password'
        option network 'lan'

config wifi-device 'radio1'
        option type 'mac80211'
        option hwmode '11g'
        option path 'platform/qca955x_wmac'
        option country 'CZ'
        option distance '9'
        option legacy_rates '1'
        option channel '13'
        option htmode 'HT40'

config wifi-iface 'default_radio1'
        option device 'radio1'
        option network 'lan'
        option mode 'ap'
        option ssid 'supi_hnizdo_2_4ghz'
        option encryption 'psk2'
        option key 'password'

cat /etc/config/network 

config interface 'loopback'
        option ifname 'lo'
        option proto 'static'
        option ipaddr '127.0.0.1'
        option netmask '255.0.0.0'

config globals 'globals'
        option ula_prefix 'fd9f:a7c0:a091::/48'

config interface 'lan'
        option type 'bridge'
        option ifname 'eth1.1'
        option proto 'static'
        option netmask '255.255.255.0'
        option ip6assign '60'
        option ipaddr '192.168.2.1'

config interface 'wan'
        option ifname 'eth0.2'
        option proto 'dhcp'

config interface 'wan6'
        option ifname 'eth0.2'
        option proto 'dhcpv6'

config switch
        option name 'switch0'
        option reset '1'
        option enable_vlan '1'

config switch_vlan
        option device 'switch0'
        option vlan '1'
        option ports '2 3 4 5 0t'

config switch_vlan
        option device 'switch0'
        option vlan '2'
        option ports '1 6t'

But I was quite surprised by it for sure. I used sysupgrade, so all the settings stayed the same (I reinstalled some package) - the only difference really was 17.01 and 18.06.


#4

Unless you've got some ancient (10+ years old, typically), disabling legacy rates will often improve performance.

I'm not sure about the distance parameter; I've never used it myself.

Adding option require_mode 'n' (or better) to your 5 GHz radio may help as well. I can't force 802.11ac, as older iPhones don't support it.


#5

The problem is not with bandwidth, the problem is that the wireless network does not come up at all. (though I tried disabling it while fiddling with it).

Any idea how I might troubleshoot the issue? When I run wifi status the 5ghz device is saying it is down, wifi up does not change that at all.


#6

Also, what is the alternative to wifi detect > /etc/config/wireless? It no longer works though I still find references to it.


#7

wifi config
your /etc/conifig/wireless may be messed up.


#8

Reading the log file will be useful here.

Distance wants a number of meters, the default is 2000. Setting distance is needed only for multi-km links. It increases some timeout times to allow for radio propagation delay.

Channel 42 should be the proper setting to run VHT80 on the lower group of non-DFS channels. If you use 20 MHz bandwidth, channel choice is less restricted. So start there to get something on the air.

I agree with @anomeome, delete your /etc/config/wireless and let the wifi firstboot script rebuild it, then set up the most minimal configuration starting from there. Either run wifi config or reboot with no /etc/config/wireless.


#9

Hm, weird. I reflashed 18.06 instead of 17.01 and 5Ghz seems to be stable again - even before I started to fiddle with the config. I swear it had not worked properly for a few hours before. I guess the first sysupgrade must have gone wrong somehow, but I have no idea how. Anywaa, thank you for your suggestions!

By the way, if that distance setting is only for long distance links, maybe the information in Luci should read something like "Distance to farthest network member in meters. Set only if it is more than 2 Km." Or something like that.


#10

The distance parameter shouldn't be set unless you really know why you need it (and yes, for anything less than thousands of metres it's actively harmful).