There’s a Zigbee rewrite coming. They say It won’t be long anymore now. You could wait for it.
There are some possibilities for expanding Zigbee coverage of Homey itself too. Like improving Homey with the antenna mod: Homey antenna mod
Waiting for the antenna’s now (AliExpress), but experiences of others in that thread sound very promising!
Try another channel for your wifi network too, as Zigbee uses the same frequency as wifi.
There’s a lot to be found in the community here. Simply use the search option (it works great) for a lot more information on this topic!
No criticism implied, so hopefully no knifes considered too… 
