Is your Mesh Client AP connecting to your Mesh Base AP?
For the mesh link you need to have 2 WLANs, one for your mesh base and one for your mesh client, both must have the same SSID and passphrase. Also the frequency used for your mesh link (usually 5GHz) must be using the same channel (this can be set in the AP groups) on both APs.
For client (smartphone) access you must have a separate SSID, the client won't receive data if it's connected to the mesh SSID. Personally I like to set client access to 2.4GHz only but this SSID can operate on both bands if required.
With a SNR of 24 your mesh link should be working.