I have several battery zigbee devices which regularly go offline. These are primarily aquara door sensors but also Heiman Smoke detectors. I have 5 of the latter Heiman but four are rock solid and only one regularly disconnects but also reconnects again without user intervention. The thing most have in common is the connection path. All troublesome devices include a Tuya relay that controls my hot water immersion heater in their connection path. I have read somewhere on this forum that Tuya/Sonoff Zigbee devices don’t act well as repeaters/routers.
Before I change drivers and other configuration it seems sensible to replace the Tuya Zigbee relay with another Zigbee relay that acts as a better repeater
Can anyone recommend a Smartthings compatible relay that is known to work as a repeater. It doesn’t have to be high current capacity as I have the existing relay linked to a contactor controlling the immersion. It does however need to be compatible with Amazon Alexa either natively or through Smartthings integration. I have been looking at Shelly 1 Gen4 or possibly Aqara T2 DCM-K01 both of which are on offer in the UK but have no experience of their compatibility and reliability.
Many thanks
I am going to toss this idea out but probably not exactly what you want. You could get additional hub(s) and create a hub group to extend coverage.
It looks like my battery powered Zigbee devices love my Woox Siren and the IKEA VINDSTYRKA air quality sensor.
I´m using Tuya (Aubess) Switch modules as relays without major problems.
Had some glitches these days but i´m suspicious on the hub firmware update to 56.11.
Which driver are you using? The correct driver can help “hearthbeating” the sensors, not letting them go offline.
I´m using Mariano’s drivers for almost all my battery zigbee devices (mainlly sensors), from different manufacturers: Aquara Door sensors (OLD), Tuya Temp/Humidity Sensors, Tuya Motion Sensors, etc…
That’s actually not a bad idea. I have a long rangy single storey bungalow which is essentially divided in half by an original 9" concrete block wall of my entrance hall. Living accommodation (Kitchen lounge dining room study etc) is one side of the “wall” and bedrooms the other. The hub which is Smartthings V3 is bedroom side of wall and I get very little problems with devices that end. (That said they are mainly mains powered devices except two Heiman smoke detectors).
All other devices are the other side of the wall. Most like the Sonoff relay on the immersion, Aurora dimmers, and switches work OK but two Aurora double sockets, two Aquara open/close sensors and one Heiman smoke detector constantly drop off. Each of these including the aurora sockets have a path through the Tuya/Sonoff relay.
If I got a second hub, how do you force the devices to connect to it rather than the original. Do you have to uninstall each device and then re-add them to the new hub? I assume I would also have to download the custom edge drivers on the new hub as well?
Hi Marcos. I am also using Mariano’s drivers for the Aquara sensors and Heiman smoke detectors. My Hub still appears to be on 056.00011 but as my hub is set to manual update I am not sure how the hub has updated to this version unless Smartthings can override this setting for major builds.
As the Sonoff BasicZBR3 is the common factor in all the devices that go offline it seemed sensible to switch this out to another known compatible brand to rule out routing issues.
The “manual update” option is for devices firmware. There are no ways to control when a hub firmware is installed 
There are two ways to run multiple hubs; each as an independent hub or in multi-hub mode. In the first, each hub has devices connected to it and processes commands for the devices themselves. To add a second hub in this manner, you would have to remove the devices from the existing hub and re-add them to the new hub.
In multi-hub, the second hub acts as just a radio repeater and the primary hub is responsible for all message processing and devices are still “connected” to it from a control plane perspective. From a radio perspective, devices will relay through the “closest” mains powered device. The secondary hub also acts as a control plane backup to primary should the primary fail. You don’t have to do anything to your devices to add a second hub in the multi-hub configuration.
Many thanks @h0ckeysk8er 
Many thanks @marcos.scheffler
Can you use a v2 hub alongside a v3 in a multi-hub setup. I appreciate V2 does not have Matter but assume my v3 hub will handle that?
Just to clarify, V2 does have Matter, it’s a Matter controller. What it doesn’t have is Thread radio so it needs a external Thread border router.
Edit: As Marcos indicates in the next comment, and also in this other FAQ “Hub Groups and Hub Backup currently only support models with Thread/Zigbee radios built-in.”. So no V2 groups.
Sadly, not. V2 hubs doesn’t support hub groups.
You CAN use both v2 and v3 hubs at the same location, you just can’t form a Hub Group. A hub group is NOT needed to solve your problem. Both of my locations have both a v2 hub and a ST Station hub and that set up works fine.
The v2 has Matter capabilities, but it doesn’t have a Thread Boarder Router (TBR). Your v3 would provide you with a TBR if needed.
The v2 has the advantage of having more memory and a quicker processor.
So if you have an old v2 lying around or can buy one cheap use it.
I use a couple of Aeotec extenders in my setup. Can’t remember but I think it is Range extender 7. For zwave, SmartThing’s Ring, Hubitat and others.
I have 2, 1 in detached garage to pick up my garage door, Pool pump switch, door sensors and detached shed doors, the other in basement for sump pump alarm, water detectors, smoke/carbon detector, camera, motion sensor. Amazon about $35.
As a note, to set up, add device, I had to one at a time near the ST hub plug in and connect , then hard power down hub, as in remove power and batteries, then added new batteries as they were well over a year old, power back up wait about 5 minuets Then moved them to a closer location, as in closest receptacle to house for garage, and closest in basement by steps.
I used the over head receptacle for Garage door opener for elevation and range.
None of those devices would connect at that range before, works great. It’s probably 50’ from Hub to garage.
So as @h0ckeysk8er suggest in his post, the V2 hub i have purchased will have to be an independant hub? This will mean I have to remove the devices which are furthest away and disconnecting from the exiting V3 hub and reinstall them (and the community Edge drivers) on the new V2 hub? Have I got that right?
I was hoping to have created a hub group but pressed the “Buy it Now” button before realising a V2 hub limitations. I did get it for a steal though 
Thanks. Haven’t searched for Aeotec extenders
Yes, you are correct. You will need to manually move devices from the v3 to the v2.
I my opinion the v2 is a better hub, so you did good.