That is true, except that 20 minutes should do it.
As far as repeater choice, you can save yourself some time: all brands are about the same with a SmartThings/Aeotec hub (the advantage of an independent third party standard) with the following exceptions:
- the EU has intentionally limited the allowable transmission power for Zigbee devices to a level much lower than the US. So most Zigbee devices sold for the US market use what is called “boosted zigbee,” giving them a longer range and possibly clearer signal. The US allows for “boosted zigbee” which has a signal strength of up to about 20. Europe however limits signal strength maximum to around 12.
This most often trips up US residents who purchase cheap devices from Ali Baba or similar global marketplaces and unknowingly end up with a European model.
I suspect, but do not know for sure, that IKEA’s repeater intended for use with their smart blinds is set to the European level because we see a lot of complaints about its signal strength.
- many Zigbee light bulbs using the ZLL profile have a problem repeating on a SmartThings network. ST engineers have confirmed this in their lab. There’s an FAQ about it, including staff comments.
FAQ: Are Smart Bulbs Repeaters? (Updated 2019: the new answer is yes, but may be inconsistent)
- IKEA Tradfri smart plugs are complicated. Many community members use them and find them to be excellent repeaters. Others, particularly in the UK for some reason, have found them to be unreliable repeaters for Aqara batterypowered devices. Not sure what’s going on there, if it’s different firmware or a bad batch or counterfeits or something else. I personally continue to recommend that people try them if they are looking for an inexpensive widely-available Zigbee repeater, but to only buy directly from IKEA, make sure you can return them if they don’t work for you, and understand the potential issue.
Outside of those three specific issues, I would expect any zigbee-certified device to have about the same performance as a repeater.
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As far as your issue with the Sonoff devices, depending on the source, you might have gotten some spec’d for the EU, and that could be the issue. If you bought them off a Chinese market marketplace, they could be counterfeit (it happens).
Also, both RSSI and LQI can be affected by many different environmental factors, even a human body standing near them. Did you check the test by swapping out the sonoff smart plug for a smart plug of a different brand in exactly the same location? One even just a meter away might have a clearer route.
SmartThings doesn’t really give us any tools for testing network quality, so it can be hard to tell what’s going on. 