This is not correct as a general broad statement. The Nuki Smart Lock is battery driven and therefore has to be more careful with (battery consuming) WiFi reconnects and might be less aggressive with reconnects than other wifi products, that you are used too. This can result in longer offline periods if your network turns out to be unstable. This is highly individual as every setup is a bit different, but the Nuki team is actively trying to include feedback into the firmware in order to further stabilize it. Therefore please make sure that you are on the latest firmware.
There are no retries.