To get back on track. I visited the location of the absent sensor again, setup my laptop watching the console and switched on a test device. Nothing.
It is in a location where there are a lot of avenues of trees…hasn’t been a problem before but may be blocking gw signals nearer to the device.
I’ll leave this here for now.
Meanwhile the other problem of the server not scheduling JOIN_ACCEPT because it added @ttn to the gateway id I have moved to a new topic so it can be more focussed,