@Playstheblues 

It is not recommended to use it in this way.

Firstly, the CPE210 is a businness product, designed for long-distance point-to-point transmission topology, while the RE, as a home product, has a relatively close signal propagation distance and is generally used for indoor WiFi expansion, not suitable for long-distance point-to-point transmission.

With the CPE210 as Client mode to receive the AP's signal, you need to ensure that the AP can transmit a long distance WiFi signal stably, and obviously the RE is not able to do this.
The classic topology is generally recommended to use two CPE210s together, one as an AP and one as a Client.