Change all your zwave contact sensors drivers to use the Ring Alarm Contact Sensor driver. There's a bug that should be fixed in 2.2.5. Spams the mesh trying to update the battery status and clogs it up till it gets a report back.
I think I have the same problem, I have varied drivers for all the devices except the thermos, tho' to no avail. The switches are Qubino's, the motion is a Heimann but it also happens to the neo- and fibaro-plugs. I thought it were the qubino's first but that has been fixed. Also put all Security off to all devices to -none- Nice little detail is that receiving data from the devices (power/state of the switch) are all reported correctly.
The z-wave is integrally down and at some point it starts working again and all is good and sweet as if I'm the fool. I feel the hub is laughing at me. And just minutes/hours later the same happens again. Also the hub is not in some sort of never ending rule loop, nor, I don't see any off the apps acting weird.
Looks very similar. Incidentally everything else including zigbee and LAN devices run 100% fine. It's only zwave that decides to take a break every so often.
I found that all of my 4 Neo Coolcam Power Plugs simply do not function as repeater (with the buildin driver ). Whatever goes through them stops right there. The plug itself though works perfectly.
When the switch changes its route it starts working again.
I now tried an other driver (not the hub-included one) to see if this would solve anything. And however the connection speed significantly drops, all the switches using the plug in its route now work.
Seems no fix even in latest update...
zWave is terribly bugged (I'm on C7).
Have Qubino16A switches & Fibaro with no such issues on SmartThings Hub (and no, will not go back tho this FUBAR). C7 bugs Qubino (S2) connected and some Fibaro. Sporadically gets better and slowly degrades so need hub reboot, then most zWave devices regain connection, though some - never.
Zigbee is with no issues whatsoever by now.