light randomly disconnects from AP and don't try to connect until power cycle

Yeelight Ceiling Light
#1

Hello Yellight,

Randomly - once in 1-3 months - some of lights disconnect from AP and don’t reconnect again to AP. Rebooting AP doesn’t help, no reconnect attempts are in ap logs. What helps is only to powercycle lamps.
Issue is happening on 5 out of 10 lamps i have always connected to power supply. They were not bought at once, but in range of approx 3 years, so could be they are different from each other internally.

example of working ones:

  • 7C:49:EB:B6:94:72 on 1.5.9_0184
  • 78:11:DC:AA:94:5C on 1.5.9_0189
    non working ones:
  • 7C:49:EB:B3:A3:78 on 1.5.9_0184
  • 44:23:7C:4E:A1:AB on 1.5.9_0189
  • 44:23:7C:4E:A1:9C on 1.5.9_0189

what can i do about it?
thank you
best regards
jano

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Yeelight Lamps constantly going Offline
#2

Seems like they now its a hardware Problem but they cant do anything against it - because otherwise they would released an update already!

#3

maybe it’s time to do hardware hacking and replace wifi part and logic with ESP or similar stuff
(i use neither remotes, nor cloud … i controll them exclusivelly over local lan)

#4

your MI ID please

#5

Hello @rex_yan1,

good timing, as i got issue just few hours before you asked, hence all is still in logs.

ID: 1797595928

Yesterday evening i powercycled one AP (due to periodical test of RDC - Residual-current device).
I was without power maybe for 10 seconds. Lights were not power cycled (are not on RDC).

According to AP log, it started booting at 2020-12-29 22:02:49 UTC (timestamp millis: 1609279369000) and already between 22:03:04 and 22:03:08 there were 10 devices reconnected already. Among them also two yeelight ceilings:
04:CF:8C:76:7B:0A
7C:49:EB:B6:94:72

But these 3 didn’t reconnect and hence had to powercycle them:
7C:49:EB:B3:A3:78
44:23:7C:4E:A1:AB
44:23:7C:4E:A1:9C
(i have always problem with these 3, also as mentioned in first message)

Hence i powercycled lights few minutes later. In AP log I see all 3 problematic ones connected to AP at 22:05:53. Note: they were powercycled together as they are on same circuit breaker.

Note: I’m testing RDCs each month, and that one AP is not on UPS yet and the same 3 lights are always having same issue…

Btw.Once in few months random one of these 3 lamps (plus 2 more on other floor) just stops communicating with AP and is not trying to reconnect again according to AP logs. Powercycling AP is not helping. Powercycling that light helps always. Once i tried to keep it like that for more than one day … but event during such long period that light didn’t connect to AP. And as I remember from past, remote control was still working.

thank you
best regards
jano

#6

and related topic: lamp stop communicated over wifi

#7

I have the same problem with firmware 2.02. On previous firmware all worked correct: after disconnect lamp connected back to wifi.

My MiID is 1555181982

I have two ceiling3 lamps

#8

@rex_yan1: any update? Could you provide schematic? Or a logic of control unit? I’m thinking of replacing it with own board with logic etc. It would save me valuable time measuring it with scope…