When M1 worked as transmitter: it support connect up to 2 receivers.
When M1 worked as receivers: 1 transmitter could connect up to 2 M1.
Only support when M1 worked as transmitter
1 single transmitter could connect with 4 smartphones/tablets
1 transmitter with 1 receiver could connect with 2 smartphones/tablets
1 transmitter with 2 receivers couldn’t connect with smartphones/tablets