Whenever you add a new repeating device to your zig been network, your other devices except for the hub won’t know that it’s there until they rebuild their own neighbor tables. So they won’t initially use its repeating capabilities. Fortunately, that’s very easy to do with zigbee. Just take the smart things hub completely off power (including removing batteries if it has them) and leave it off for at least 15 minutes. During this time leave all the others zigbee devices powered on. This will cause the end devices to go into “panic mode” as they realize that the Coordinator is not available.
Then when you power the hub on again, as each individual device reconnects it will rebuild its own neighbor tables fresh. This whole process can take a while, so you may not see an improvement until the next day. But it should cause your network to then route efficiently using all the available repeating devices.
Basically, any time you move a device to a new physical location, you probably need to rebuild the neighbor tables in this way. This is called “healing the network.” 