This is correct, mesh support on T300 started with 9.10 version and above. This is why you are not getting the mesh option.
Please upgrade the ZD to 9.9.1.0.52 and then to 9.10.2.0.114 for T300 mesh support.
As per release notes of 9.10.2, T300 and 7762 both are supported on it.
https://support.ruckuswireless.com/documents/3266-zonedirector-9-10-2-mr2-refresh8-release-notes/dow...
Syamantak Omer
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