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Unreliable OVMS2 connection

I'm getting unreliable OVMS connections. More often than not, I find it in connection failed, waiting to reconnect state. https://flic.kr/p/2mY1V4P

Can I only diagnose this by installing an SD card and turning on logging? Or can I "dmesg grep [something]" to get relevant history?


From shell, I see repeated

From shell, I see repeated entries of:


E (254123) ovms-server-v2: mg_connect(ovms.dexters-web.de:6870) failed: cannot parse address

E (254123) ovms-server-v2: Status: Error: Connection failed

I (254243) webserver: HTTP POST /api/execute

I (254243) webcommand: HttpCommandStream[0x3f8b7b38]: 3515000 bytes free, executing: server v2 status

I (254293) webserver: HTTP POST /api/execute

I (254303) webcommand: HttpCommandStream[0x3f8b2d1c]: 3513172 bytes free, executing: server v2 status

I (301113) housekeeping: 2022-01-19 07:23:24 GMT (RAM: 8b=89036-89684 32b=10160)

I (306143) webserver: HTTP GET /status

I (308113) ovms-server-v2: Connection is ovms.dexters-web.de:6870 RK17XWO

I (308113) ovms-server-v2: Status: Connecting...

I (313133) webserver: HTTP GET /status


All connections are up, module AP, cellular, and module connected to my wifi ... though I find that accessing via my local network on 192.168.0.xxx rarely (but not never) works, even when wifi connected...?

dexter's picture
Unreliable OVMS2 connection

You need an SD card to store the log. The shell shows the same log entries so can also be used, but only when the module is accessable via HTTP.

"cannot parse address" may be a DNS error. Try setting a fixed DNS server.

Your module constantly switching networks could cause this as well -- you mentioned a poor Wifi connection in the other thread. Check your typical Wifi signal levels ("wifi scan" / monitor on status page) and your wifi settings (good/bad thresholds).

Thanks for your continued

Thanks for your continued help.

I've improved the wifi signal a bit. It's not great, but it isn't that bad, it's -88.3 dBm at the moment. The thresholds are set to tolerate that with bad signal set at -100 dBm.

I'm starting to think i've got a hardware problem, a dodgy network interface or something. It takes quite a lot of time after reboot to get back to the web ui on the module's AP. Getting it on the local network is flaky as anything and rarely works, even though it's got an allocated IP address from the home network fine.

I've switched to google DNS server static and i'm collecting logs...

and i'm getting lots of

and i'm getting lots of crashes, due to watchdog, or ovms-duktape usually I think:


Last boot was 127 second(s) ago Time at boot: 2022-01-19 21:45:27 GMT This is reset #99 since last power cycle Detected boot reason: Crash (12/12) Reset reason: Task watchdog (6) Crash counters: 1 total, 0 early Last crash: abort() was called on core 0 Backtrace: 0x4008e676 0x4008e911 0x400e93f8 0x40084152 WDT tasks: IDLE0 Version: 3.3.001-33-g58d01654/factory/main (build idf v3.3.4-848-g1ff5e24b1 Dec 27 2021 00:03:08)

Firmware: 3.3.001-33-g58d01654/factory/main (build idf v3.3.4-848-g1ff5e24b1 Dec 27 2021 00:03:08) Running partition: factory Boot partition: factory Factory image: 3.3.001-33-g58d01654

dexter's picture
Unreliable OVMS2 connection

-88.3 dBm actually is pretty bad, no wonder your connection is unstable.

My car is in my garage, 2 levels below my apartment, and I've got -78 dBm right now. Try optimizing the Wifi channel and the placement of your router / repeater.

The default threshold for a too bad to use signal is -89 dBm, and the default for a usable signal is -87 dBm, so you're very close to unusable.

Depending on the actual environment you may (!) be able to get a stable Wifi connection at levels below -89 dBm, but you normally won't.

Setting the thresholds to tolerate -100 dBm doesn't mean you'll get a usable signal, it just means an unusable signal won't be detected by the system.


dexter's picture
Unreliable OVMS2 connection

PS: in the other thread you wrote you checked the "Immediate disconnect/reconnect" box. That's also not recommended for your situation. It's meant to speed up switching to another network that comes into reach while moving the car. In a poor signal situation it means you will have lots of unnecessary disconnects.

The default configuration is the default for a reason.

Ok, so I have put a dedicated

Ok, so I have put a dedicated AP in the window firing out to the car! :-D

It's old, and the OVMS is still down in the footwell, but it's showing -70 to -75 dBm signal levels. I've unticked that "Immediate disconnect/reconnect" box.

Cellular use has been about 100KB since I set that up last night.

Local lan access is more stable.

But i'm still seeing a lot of gsm-nmea, gsm-mux, cellular traffic in the shell. I have been logging since last night.

I've been up for 32000 seconds (almost 9 hours) now without a crash...

dexter's picture
Unreliable OVMS2 connection

Your wifi signal is excellent now, but cellular usage should be much less then. As you've got the module log now, please send it to me by email for analysis.

gsm/cellular log entries don't necessarily mean traffic, many log messages are produced for the connection state.


Many thanks, will do.

Many thanks, will do.

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