I have two RB01's (11/2021).
By default the device comes in netmode:0, so the method failed.
Master device became netmode:4 when other device was in mesh mode. The other device, meanwhile, became netmode:3.
Also in netmode:3 the method failed.
Telnet was activated without any problems. (netmode:4)
So, method succeeded only when netmode is 4.