Just set up a 303H with latest firmware (6.5.4.5). Single AP environment. If the band is set to ALL, the AP doesn't recognize any device as even having AC capability. The devices are connecting to 2.4, even right next to the AP and getting a max throughput of about 45mbps. If I limit the band to only 5GHz, then the devices connect properly and are identified as having AC capability. I’ve tested with both IOS and Win 10 devices.
A fresh restart doesn’t help. Rebooted all routers and switches.
If I change Band steering mode to Prefer 5GHz, the devices connect to the 5GHz. The problem with this is that they are connecting to 5GHz even when they are too far away and should be connecting to 2.4. With the RAP109, latest firmware, and band steering Disabled, the device selected the correct frequency based on conditions. And I am also able to get about 85Mbps with the RAP on 2.4.
Update: After the AP-303H has been up for about 15 minutes, it seems to be working correctly. Does it really take this long to fully boot everything?
Switching the band to 2.4 only and then reverting back to All, the condition is reset to only connecting on 2.4