Been trying to figure out what exactly the SOLO firmware is for. I have just one R500 AP. I've searched the forums, FAQ and Google, but there is nothing that explicitly states what the SOLO firmware is for.
We ship a '901--US00' part number AP with Solo/Standalone firmware, like 220.127.116.11.1347 that looks like an AP WebUI interface when you login with default 'super'/'sp-admin' credentials. You can configure individual SSIDs on both 2.4g and 5g radios (16 each) and they assume you have a DHCP server and Def-gw router on the network. This Solo AP firmware will also allow the AP to connect to a ZoneDirector or SmartZone controller, via DHCP option 43, DNS, set director AP command, etc.
The '9U1--US00' part number APs ship with our Unleashed firmware (currently 18.104.22.168.47) and the code will not look at the DHCP/DNS options or join a ZD/SZ controller, they will look for an existing Unleashed network or advertise their Configure SSID to allow you to connect and create one. An Unleashed AP network can exist on the same LAN as ZD/SZ (like in my office lab), though not a typical deployment.
You *can* do a factory default on an AP running any code, access it via default IP, and install/upgrade/change the code to Solo or Unleashed, as you have need or for testing. But Support contracts (opening a case with Ruckus) is different between a Controller based network (support for ZD/SZ) or Unleashed (support for up to 25 APs). If you ever need an RMA (return material authorization), you will receive a same '901' or '9U1' replacement AP, no matter what code you were using on it. Is that helpful?