I’m having a similar issue as the others on HA 0.82.0b3. I’m having such errors:
This started to happen since 0.82 version. Token is correct - double checked. Additionally, some more Xiaomi devices started to disconnect like power strips or Air purifier 2. It works again when it’s powered off and on.
Find out what channel your 2.4g wifi is using.
Then find the zigbee channel your gateway is using
Then look here to see if they are over lapping
try and move your 2.4g wifi channel as far away as possible from the zigbee channel as described in the above article… i did this and rarely get unavailable sensors etc
Hi guys,
I had this issue and tried everything! The thing that solved it was a replacement router.
I found this after bringing my hass pi3, Xiaomi Gateway and a motion sensor to work, set them up in the morning on the work WiFi and seeing no dropouts after the whole day.
I was using an ISP supplied ZTE ZXHN H298N, which it turns out was either ignoring or filtering out the multicast heartbeat messages coming from the Xiaomi Gateway.
Got a TP-Link AC1750 Archer C7 and it all started working out of the box. No dropouts since (been 4 weeks now).
So, try taking a bare bones setup to another network to see how it performs. Worth a try!
Had the same issues on 0.82. On 0.80 everything was working fine.
Changed my config from:
xiaomi_aqara:
gateways:
- key: !secret xiaomi_key
to:
xiaomi_aqara:
discovery_retry: 10
gateways:
- key: !secret xiaomi_key
mac: 11:5c:77:98:17:b2
and so far it seems to be working again 
The mac above is a random one and not my actual mac 
Hey,
Is it still working without issues?
Hi,
In my case yes.
need to remove the colons - these are not supported here:
(string)(Optional)The MAC address of your gateway. Needs to be formatted without “:”. Optional if only using one gateway.
Yep still working without issues.
You’re right, that part probably doesn’t do anything in my config 
Is it still working for you?
Mine seemed to work fine, but it’s showing as unavailable more frequently lately…
Yep it’s still working here.
same here, unavailable problems… Do you have the same status (offline) in Mi home?
Nope… In the MiHome app they seem to work fine.
That’s very weird, I have never seen that happening before then I moved it to a new network (wlan0-1 on OpenWRT) and I was having issues with invalid key which I got fixed by having a multicast proxy installed .I though that was the reason I was getting it to show Unavailable but woke up this morning to see the gateway in that state and the multicast packets are still getting received by HA so not sure what’s going on.
I also have this problem, have been having it (primarily motion sensor) for many many months now, maybe 6?
Do you see this with Aqara devices connected to a Aqara gateway or devices connected to a zigbee USB stick?
I have the theory that this has got to do how aqara sensors work. Maybe they want some keep alive handshake every hour or so. They want to save battery so they have got a mechanism to fall asleep.
Maybe it can help
all the problems I had solved after I updated gateway to the latest version.
I’m having this problem with Apple Airport devices on the latest firmware… No idea what to do as I don’t have these options. My hass server is already connected by ethernet.
I had this problem recently. Went to hell and back trying things.
The solution was to change my 2.4ghz router setting to use channel 11 and not 8.
Then all worked perfectly again.
Hope this helps someone.
Hi, I have Gateway 3 (round) and it gets unavailable randomly, for few seconds only and just in HA. Including subdevices. Any idea how to work with it? Get new hub? It seems to be as a problem described here