I have been on channel 20 since April 2018. It has been working great for me. My advice based on experience and everything I've read says to avoid the highest channels, particularly 26.
In choosing channel 20 for myself, I looked at trying to keep interference from my 2.4GHz WiFi at a minimum. See my post here for an initial explanation of how ZigBee and 2.4GHz channels overlap, but there's loads of more detailed info among the Hubitat forums and elsewhere.
Probably, but unless you've got an XBee or the Hubitat getchildandrouteinfo feature (view http://your.hub.ip.address/hub/zigbee/getChildAndRouteInfo, see here for more info) works to see if newly paired Xiaomi / Aqara devices are connected via your Swann Smart Plug, there's currently no way to positively confirm the outlet is not a "friendly" repeater.
The reason why Xiaomi / Aqara devices work on Homey is, as I understand it, that modifications to the ZigBee stack can be community driven. So they were able to bend and break rules as it were, to force compatibility by making exceptions to how certain aspects of ZigBee is meant to operate.
A number of key Homey users have also spent countless hours reverse-engineering how Xiaomi / Aqara devices communicate with a native Xiaomi / Aqara Gateway hub through trial, error, and guess work, all because Lumi United Technology opted to create proprietary formats for many of the ZigBee messages the devices send and receive, instead of following the published specifications by the ZigBee Alliance.
Hubitat is a private company, and so they are free to choose which devices they support, and the honest truth is that Xiaomi / Aqara devices are a hot mess in terms of providing support while at the same time maintaining support for the vast numbers of ZigBee devices that follow the publish spec.
If there were ways to help towards full compatibility in the Hubitat drivers you can bet I would have added that ages ago. But unfortunately, Xiaomi / Aqara devices are completely inflexible in allowing their networking parameters to be adjusted.
It's important to mention that Athom's ZigBee implementation for Homey is far from perfect and has its own host of issues. And if you go searching, you will find that the same issues Xiaomi / Aqara devices have with most repeaters also exist on Homey. See here, for example:
Athom is not using Zigbee Shepherd; an open source implementation of Zigbee for Homey.
This was one of the fastest, and at that time best, options to implement Zigbee on Homey...Zigbee and Z-wave appear quite similar, but the Z-wave association certifying devices is controlling the implementation more strictly then it’s counterpart for Zigbee...
a result is that the Zigbee devices have more custom implementations; the Xiaomi Zigbee devices are a typical example of it...In order to be able to support all these custom implementations, Athom already updated it’s Zigbee Shepherd implementation to a level that it is no longer compatible with the open source branch....
From specification perspective Z-wave and Zigbee are quite similar; Z-wave with their command classes and Zigbee with their clusters...
The Zigbee re-write will therefore (most likely) mean a complete re-write of the Zigbee core (abandoning the Zigbee Shepherd) and Zigbee meshdriver, but based on the latest Z-wave core structure, approach and meshdriver...
That quote is from a year ago, and as far as I know, Athom hasn't finished their ZigBee core rewrite and users are still having mesh issues. Also, IAS support, needed for smoke / gas detectors and some other devices, isn't implemented.
TL;DR: Hubitat doesn't support Xiaomi / Aqara devices because those devices don't fully support all aspects of the ZigBee specification. And if you read through their forums, at this time Homey is not looking so homey for Xiaomi / Aqara devices either.
I have a number of the Aqara Wireless 2-button Switches, both the 2016 and 2018 revisions, and I have only seen them drop their connection a few times. Count on one hand few. And response time is immediate; the first time I press after days of no use, the lights turn on / programmed action is taken.
As @bertabcd1234 says, the issues you're describing with your Aqara Wireless Switches sound like a problem with repeaters that don't work with Xiaomi / Aqara devices. Although in most cases, the repeater drops the Xiaomi / Aqara devices' connection (and the Xiaomi / Aqara device does not rejoin as asked to), I have also personally witnessed a repeater only sending some messages from a Xiaomi / Aqara device onward to the hub.
So what ZigBee repeater-capable devices do you have?
