The IAP-207 and AP-207 share identical hardware. The difference is — IAP ships with Instant firmware; AP ships with Campus (controller-based). You can convert a CAP to IAP using a console cable and a TFTP-served Instant image, if you can legally obtain it.
Aruba produces two distinct types of firmware for the 207 series: aruba iap 207 firmware free
Here is your guide to finding and installing the firmware safely without paying for a support contract you don't need. The IAP-207 and AP-207 share identical hardware
Download Aruba IAP 207 Firmware for Free! it is very stable
Once configured, it is very stable, though some users report it needing a monthly reboot due to heat.