IAP 105 and IAP 205 needs to be on the same software version to form a cluster.
Since IAP 105 is not communicating to the cluster now, Try to isolate all the IAP105 and first upgrade them to the same version, that IAP205 is running.
You can try the below version from Conservative Release
Release 6.4.4.8-4.2.4.15
For IAP-105: ArubaInstant_Orion_6.4.4.8-4.2.4.15_72892
For IAP-205: ArubaInstant_Taurus_6.4.4.8-4.2.4.15_72892