Please kindly check the following:
1. Make sure the client app/software is for InstaShare 2.
2. Make sure to enable the ports which are needed for InstaShare 2.
3. Make sure the client app/software and the host on BenQ display are connected to the same network.
4. When client app/software and the host on BenQ display are in different VLANs, make sure that the network of the school/enterprise supports inter-vLAN connection.