I have a location that has a bunch of ap130 and ap650 and we added a bunch of ap4000 to give us a more dense coverage. I upgraded all the access points to 10.5.5 so we could have the same firmware across the entire campus. Extreme support did say that as long as the firmware shows up as latest firmware, it will be compatible. We have four different SSIDs on three different networks and only one of them was accessible on the ap130 after the upgrade. After a bunch of troubleshooting and testing on multiple ap130s, I finally decided to downgrade the firmware to 10.0.10.2 (this was recommended as the best firmware for the ap130 years ago). Once it downgraded to this one, everything worked like a charm.