There is a lot of discussion on this but is didn’t “Search” a definitive answer.
As usual I’ll probably get what I need from @JDRoberts ! 
I have been battling for years with XIAOMI devices dropping so I bought 2 Tradfrei wall outlet repeaters; proven to work with these devices.
I delete and add the XIAOMI devices at my hub (IDE says next hop “Hub”).
I place them back in their physical locations around the house and expect them to find a path back through the repeaters if they deem necessary (signal too low, bad route path etc.)
Either they stay “Hub” or run the gambit of other device not near them instead of the proximity placed repeaters.
This device is just down the hall from a newly installed repeater but it traverses the second floor of the house and then to the far end of the first floor before coming all the way back to the second floor hub!
[This Device (2B9E) ]↔ [Living Room Motion (047E) ]↔ [Back Door Light (0A65) ]↔ [Home Hub]
What is the logic on routing, can I force a mesh reroute?
I did try to replace all the moisture sensors this year with ST approved ones but COVID has killed all the production/supply so this was a cheap attempt at a resolution.
Yeah, that’s not how Zigbee routing works. 
Zigbee Devices being newly added to your network choose a nearby available repeating device as their “parent“ and from then on they always try to route through that device. Or go direct to the hub if that’s available.
Since you paired the devices in a different location than where you are going to use them, they are not selecting the right parents.
You need to pair them in place where you expect them to operate. that should give you the most efficient network.
Ah, I did try that first but Xiaomi and ST being as cranky as they are together yielded no pairing.
I’ll try and try again as my first assumption was that they needed to find their way to the hub through the repeaters not rediscover after relocation.
You can try unplugging your hub for 20-30 minutes. This should cause your Zigbee devices to search for the hub, and find the relay devices. When you plug in your hub, they will likely connect in a better pattern.
They might also find a better path if you give them some time. I have a ST moisture sensor that found a nearby Peanut Plug and now uses that as a relay after leaving them alone for about a week.
I did try that earlier and one moisture did find the repeater.
I have come to the conclusion that Xiaomi motion sensors don’t like even the Tradfrei repeater.
I can not get a single one to recognize them even when paired right next to the repeater. They will pick hallway switches way down the other end of the house or connect ot the Hub directly even when staring at the repeater.
Sad this line of devices didn’t go “Full Zigbee”, for the price you can do a whole home for 100.00
do yourself a favor and throw the Xiaomi devices in the trash. The cheap price isn’t worth the hassle. Get something that conforms to Zigbee HA 1.2 or Zigbee 3.0 protocols.
I like them when used with their own gateway and then used with Homekit. It’s a US server if you are using the new little camera as the base station, customer support is very responsive, and the devices are nice as well as being inexpensive.
But I agree they just are not reliable enough when used with other zigbee hubs.
Agreed.
I did get fed up many months back and tried to order 6 ST moisture and 6 ST motion but the Covids dried up everything.
I’ll ping my supplier and see it China is back to work yet
i’ve had good luck with the Sonoff zigbee sensors. They are a similar price point, but sadly no leak sensor in their lineup.