Erratic connection after pairing to a second wifi network

[breboulet]

Hi Dave,

Here are the steps to reproduce the weird behavior I ran into:

• Start RPi4 from a clean comitup image
• Comitup Hotspot shows up -> Connect to Wifi-Network-1 -> Success -> everything's happy, even across reboots
• Turn Off RPi4
• Turn Off Wifi-Network-1 (my Mac Mini's w/ Internet Sharing On)
• Turn On Wifi-Network-2 (my usual Wifi Router)
• Turn On RPi4
• Comitup Hotspot shows up -> Connect to Wifi-Network-2 -> Success (or what looks like it)
• 'ping google.com' produces erratic/random response times (sometimes 30ms, sometimes 6000ms+) <-- this doesn't happen on first pairing
• On reboot re-connection seems slow
• If I switch the networks again (Turn Off Wifi-Network-2 and Turn On Wifi-Network-1), hotspot shows up, even if repairing, connection fails

I couldn't pin down what the issue was, nor find any relevant logs, but something fishy is going on with the network after that second pairing. CPU usage seems normal. That's a tricky one...

Hopefully you'll be able to reproduce the issue and understand what's going on a little better than myself!!

And thanks again for that wonderful project ;)

Best, Bastien

[davesteele]

See CONTRIBUTING for logging and reporting notes.

[breboulet]

Hi Dave,

Here's my test environment:

• Stock Raspberry Pi 4 2GB with built-in wifi (no secondary dongle)
• Comitup (non-lite image) generated via stock (no code change) https://github.com/davesteele/pi-gen with comitup v1.21-1 (see 2021-04-26-Comitup.info.txt for full image info)
• Two Wifi Routers (WifiNetwork1 is a MacMini sharing its internet connection - eth to wifi, WifiNetwork2 is the real router)
• I had to plug the RPi to a monitor (hence the non-lite image) since I couldn't ssh into the broken RPi because of the network issues

Steps to reproduce:

• Turn On WifiNetwork1
• Turn On RPi
• Comitup Hotspot shows up
• Pair to WifiNetwork1 successful
• Turn Off WifiNetwork1
• Comitup Hotspot shows up
• Pair to WifiNetwork2 unsuccessful/partial (couldn't even get to the erratic connection this time, it simply wouldn't connect to WifiNetwork2, Hotspot not showing up). Connection seems to be added to nmcli c though.
• Reboot, same behavior: can't connect to WifiNetwork2, no hotspot
• I tried comitup-cli: it shows the old connection WifiNetwork1 has the "connecting" one, even if I try to manually delete it (via comitup-cli) it wouldn't delete it. 'nmcli c' still shows both connections. I have the feeling that it would keep trying to use the very first connection no matter what.

Note that individually (not in sequence, from scratch) connecting to WifiNetwork1 or WifiNetwork2 works without any issue.

Here are all the log files I collected while running the above steps: comitup.log comitup-web.log daemon.log syslog.txt

Hope this helps.

Best, Bastien

[davesteele]

The daemon log indicates it is a known problem in recent versions. Upgrade or install 1.22-1.

[breboulet]

I confirm the problem is resolved with 1.22-1 Thank you so much! Best, Bastien

[breboulet]

Hi Dave,

For some weird unknown reason the problem is back there, after reboots it connects to wifi, but shorty after connection becomes unstable until it drops completely. Using comitup-1.22-1.

See the new logs attached: syslog.txt comitup.log comitup-web.log daemon.log

[breboulet]

Here are more logs hat I gathered after letting the Pi run for a while. I thought they might be helpful. If you need anything else, please let me know ;) syslog.txt daemon.log comitup-web.log comitup.log

[breboulet]

Hi Dave,

Unfortunately I think the issue is back with comitup 1.25-1. Note: I have the following comitup.conf set: enable_appliance_mode: false

I also noticed that, even when the connection works, the Pi has always 2 different IP addresses on the wlan0 interface, is that normal? (seen across multiple versions of comitup)

Best, Bastien

See logs attached: comitup.log comitup-web.log daemon.log syslog.txt

[breboulet]

The double IP problem seems to be caused by dhcpcd.service If I mask it, I then see a single IP address after reboot. Unmask it and double IP is back.

[davesteele]

The comitup image has dnsmasq.service, systemd-resolved.service, and dhcpd.service masked.

[breboulet]

It does have dhcpd.service masked, but it doesn’t have dhcpCd.service masked.

[davesteele]

Concerning the double IP, I'm guessing you have a dhcp service connected to the hotspot? That could cause problems regardless of Comitup's behavior.

[davesteele]

V1.27-1 is in the archive, but not the repo (yet).

[breboulet]

Thanks Dave, I’ll give it a try when released in the repo and let you know ;)

[breboulet]

I generated a new image with 1.28-1 and even though comitup-cli states it's in HOTSPOT mode and lists the nearby wifis, the actual hotspot does not show up on my iPhone's wifi network list.

[davesteele]

1.29-1 released.

[breboulet]

It works!!