Problems setting up Aeotec dimmers

I have a number of Aeotec dimmers and switches around a large apartment. They all worked just fine with the previous ZWave controller, I’ve taken down the old network and am trying to build a new on on the SmartThings hub.

Some devices work OK. Some work for a while, then go offline; I have examples of this where one is working, 3m from the hub, while another which is behind the same switch, drops offline.

Others, and this seems to be the more distant ones, configure just fine but never respond. Any commands just results in ‘network error’.