First rule of home automation: “the model number matters.”
In the case of zigbee, unlike Z wave, each zigbee device will choose a “parent” repeater And then will send all of its messages through that parent.
The problem is that it is up to each individual manufacturer to decide how many, if any, children one of their devices will accept. For most inexpensive home automation mains-powered devices this is around five, but it can be as low as three and it is rarely more than seven. Sometimes, such as with Sengled bulbs, it’s even zero. For smartthings hubs, the number of children directly attached to the hub is 32 for the first generation and 64 for the newer ones.
There are people who bought a bunch of Sengled bulbs, didn’t have any other Zigbee repeaters, and found that they couldn’t add them all to their network because the hub had run out of child slots.
All of which is to say depending on your total network layout, you may not be able to force a zigbee device to use the hub as its parent.
Also, I’m confused about what your devices actually are. Osram only makes Zigbee devices, which is why I just went into this whole discussion. But most of the other posts in this thread have been talking about Z wave devices.
Zigbee repeats only for zigbee and zwave repeats only for zwave.
So what’s the specific brand and model of the device which is not functioning well?