That’s impossible right, one hour in and the status page still says everything is fine… 
Seeing the same 503 errors. Occasionally starts working. But all my devices stopped sending events at exactly 11pm pacific. Down for 90 minutes now, can’t turn off the lights and house fan. 
Tried the 30 sec ethernet unplug, no joy. I don’t have a bridge, but I do use erocm123 : Inovelli 2-Channel Smart Plug.
How do I get devices working again?
Should I have already received this update (in Australia?).
My hub is still on 000.025.00050
I’m trying to resolve a z-wave issue and I’m hoping a firmware update will help - if I can get the update!
Checking back on the board and tried the “Disconnect LAN cable for 30s and reconnect” workaround and my MQTT bridge is working again. Thank you @BarryA and the gentlemen who reported that this worked for them. It’s working for me until supposedly the SmartThings hub is reboot (according to @BarryA in a message above this).
Awaiting a real fix, but I can live with this workaround for now.
Yes, you can try sending a “Hub Disconnect” command from the ST Web IDE, under My Hubs, Utilities. This has worked reliably for me to reestablish communications via port 39500. The hub will automatically reconnect after about 30-60 seconds.
I am getting this exact same issue.
Thanks! That worked
Nice work Samsung, half my lights and door open/close sensors are showing offline in the Classic App. I’m seriously contemplating having my own Zigbee/Z-Wave server at home lately.
I was struggling with this topic with a private Fully Kiosk device handler using REST communications. I was building out the DH and my temporary unsolicited message solution was using the External URL REST interface with webCoRE using JSON. Until it wasn’t - when I (again) realized that webCoRE is a functional application like any other SmartApp you can design and publish. In this case, why just not use webCoRE since other SmartApp or DHs with small exception run in the cloud, and the hub is just a pass-though? This allowed me to use the native JavaScript XMLHttpRequest() at the device and bypass the hub pass-though. And webCoRE makes it so simple to debug logic and of course interact with other DHs, without worrying about your own OAUTH2
So IMHO - having multiple very smart SmartApps make things more difficult to control the whole home for automation: Use DHs as dumb devices with simple SmartApps; then use webCore for as much logic as possible; then attach view solutions such as ActionTiles, Alexa or Google Home with as little logic as possible.
Hows the 39500 fix coming? 
Thanks!
The ‘Disconnect Hub’ trick worked for my MQTT.
Very good discussion points @bloodtick_jones and @ogiewon.
However, while a great project that really made ST viable for me, WebCore creates dependencies on internet for HA. Which is really why a native, local, rules engine is so critical for a well-automated (read: beyond lights off and on) home that is smooth functioning (read: devoid of familial embarrassment). When things go haywire due to an evil firmware release or an internet blip, it’s messing with my home-life-work balance. Sounds like the people with this view left SmartThings for Hubitat. Too bad.
I resemble this 
remark
I would hope that there is little disagreement [here] that as much local control as possible when the internet drops offline is a better design architecture. My design objectives with home automation ensure that the original get up and turn the light on/off via the same way you did it 5 years ago is sustained. This does take some work, but keeps the household from taking any position on ‘get rid of it’ because I softly remind them they could always get up and turn the light on/off - and the broken ‘thing’ is really a convenience. Moving to HA would be another effort in this similar direction. IMHO.
However, my true objectives in IoT (and hopefully some others here) are around home artificial intelligence such as Alexa (Conversational AI). I am not seeing HA solving that problem - so I personally am not in a rush to jump off ST and invent my own similar wheel, but respect those of you that do.
I am having the same issue. All my lights are on and not working. Same for my sensors. I’ve removed them from the app but they aren’t showing up to re add them.
I spoke too early. Things are back down… All zigbee devices… 2 Cree bulbs… 2 door sensors
Are the Cree bulbs your only Zigbee repeater devices? If so, I would replace them with Sengled bulbs (non-repeaters) and add a few Zigbee outlets (e.g. Samsung Outlets, Peanut Plugs, Tradfri outlets, Iris 3210-L outlets, etc…) as Zigbee repeaters to establish a solid mesh network.
The Cree bulbs are known to be poor Zigbee HA repeaters. I got rid of my Cree Connected and GE Link bulbs and my Zigbee problems disappeared. I use Iris 3210-L outlets, but these are becoming harder to find these days.
Sure Dan. Will note your suggestions.
But the point is: things were fine for last 2 3 years until the latest Firmware updates.
Thanks for the suggestion.
This worked for me as well.
If you removed them, then you need to reset/exclude the devices so that you can re-add them. One suggestion, don’t delete the devices, it just makes more work.