Cannot connect anymore zigbee devices

I have 17 zigbee devices connected to my homey (12 routers, 5 end devices). I cannot get it to add any more devices. I have tried connected different devices, i have tried connecting various things, both an Ikea bulb, Ikea Switch, and an Aeotec Multipurpose Sensor (IM6001). None of them can connect.

Can it really be true that the Zigbee connection in Homey Pro is that bad?! My Smartthings hub was better than this.

Try turning off all other zigbee apps but the one you need for the new device and try again. Sometimes unplugging all Ikea lights prior to pairing, helps as well.

What about this? Zigbee fully down - #2 by matrover