Hi,
Can you check and confirm below
1) 515 is not running in standalone mode
2) Auto join is enabled
3) 303H is not running in standalone mode
If you are able to see the Setmeup SSID, it means 303H made his own
cluster. Currently is 515 and 303H in the same Vlan? if no, and you put
them in the same Vlan, what happens? 303H doesnt come up?