I've had a C7 for a few years and all has been great until recently, I've had issues pairing new devices. I thought it was related the devices not being close to the hub or a pour network setup... But after reading some posts, it could be related to the 170 ghost devices I have on the network...
I tried every suggested option to remove the devices. I got a Zooz ZST10 (500 model) and couldn't get it to pair with the hub. I'm kind of stuck at this point. Any suggestions? I've even considered wiping and repairing the ~30 devices I have.
Considering that you have a record breaking number of ghosts that is 6 times more than actual number of devices, I would strongly recommend resetting the radio and starting over.