Hi Richard,
If you install a new ATOM site, or make certain changes to your existing setup - such as changing the Raspberry Pi or installing a new or reloaded software card - your ATOM unit has to 'ask permission' to connect to (or connect back into) the network. This request has to be noticed and actioned manually by one of a relatively small group of network administrators. Whilst this normally happens fairly promptly, I know one of them has been away this week and the others pretty busy, so I guess that was the reason for the (relatively modest) delay on this occasion.
Glad to see that all now appears to be well.
Best Regards
Peter