dankcushions
Posts: 27
Joined: Sat Jun 13, 2015 10:40 am

DHCP/wifi issues (pi4, buster)

Sun Jan 19, 2020 5:18 pm

Hi!
For some reason my new pi4 seems to be struggling with connecting the wifi. At one point I was able to connect very intermittently, but it was quite laggy through SSH, and now following a reinstall I'm not connecting at all. because of this i can't paste any output to here, but I can access the terminal directly. some findings so far:

wpa_supplicant.conf:

Code: Select all

country=GB
update_config=1
control_interface=/var/run/wpa_supplicant

network={
 scan_ssid=1
 ssid="mynetwork-2G"
 psk="mypassword"
}
in /var/log/syslog dhcpd gives a couple of "time out" messages, before forking to the background.

if i run

Code: Select all

iwlist wlan0 scan
i can see that said 2g wifi network is on channel 11, quality 48/70, signal level=-62dBm. not sure if those are deal-breakingly bad? i have plenty of other wifi devices in the same location that have good signal.

i have no idea how to troubleshoot this. please help! :)

epoch1970
Posts: 5729
Joined: Thu May 05, 2016 9:33 am
Location: Paris, France

Re: DHCP/wifi issues (pi4, buster)

Sun Jan 19, 2020 5:28 pm

48/70 is not great but I can’t recall if that is above or below critical.
Do you need scan_ssid?
https://w1.fi/cgit/hostap/plain/wpa_supplicant/wpa_supplicant.conf wrote: # scan_ssid:
# 0 = do not scan this SSID with specific Probe Request frames (default)
# 1 = scan with SSID-specific Probe Request frames (this can be used to
# find APs that do not accept broadcast SSID or use multiple SSIDs;
# this will add latency to scanning, so enable this only when needed)
"S'il n'y a pas de solution, c'est qu'il n'y a pas de problème." Les Shadoks, J. Rouxel

dankcushions
Posts: 27
Joined: Sat Jun 13, 2015 10:40 am

Re: DHCP/wifi issues (pi4, buster)

Sun Jan 19, 2020 5:34 pm

Do you need scan_ssid?
probably not! i removed that line and rebooted... still the same dhcpd timeout

epoch1970
Posts: 5729
Joined: Thu May 05, 2016 9:33 am
Location: Paris, France

Re: DHCP/wifi issues (pi4, buster)

Sun Jan 19, 2020 5:48 pm

Mhh.
I would try to “denyinterfaces wlan0” in dhcpcd, reboot. Once rebooted, from the command-line, as root, run wpa_supplicant on the interface, in the foreground, in debug mode. You’ll see if authentication succeeds or fails.
https://manpages.debian.org/buster/wpas ... .8.en.html

If it succeeds, reinstate wlan0 in dhcpcd, reboot and try again. If DHCP fails, perhaps the DHCP server rejects the requests (unlikely) or the wireless signal is too weak.

Also, make sure you are using a proper PSU to power the Pi. If the computer has power issues all sorts of random things may happen.
"S'il n'y a pas de solution, c'est qu'il n'y a pas de problème." Les Shadoks, J. Rouxel

dankcushions
Posts: 27
Joined: Sat Jun 13, 2015 10:40 am

Re: DHCP/wifi issues (pi4, buster)

Sun Jan 19, 2020 10:30 pm

welp, running in debug mode made it very obvious where my problem was - I had a typo in my network name :oops:

it seems to be stable right now, with none of the lag before, but quite what caused that i don't know! i'm using an official power supply but i am running inside the aluminium FLIRC case that may be affecting the signal quality.

so far, so good! thanks for the help!

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