The devices whose status unknown are the ones which are not discovered in DA.
CAPC might have pulled the devices list from Spectrum for discovery and due to some reason the discovery of the devices was not successful. And DA doesn't know about these and hence will not poll them for any for the metrics. This is the reason why the status of the devices is UNKNOWN.
To get the list of such devices, run the below query from CAPC putty session:
mysql -P3308 netqosportal -t -e "select itemid, itemname, v6_ntoa(address) from t_device where itemid not in (select itemid from dst_device where sourceid in (select sourceID from data_sources2 where ConsoleName like '%Data Aggregator%'))"