Hi Ben,
If I do this on a machine without local rtl-sdr that does work. If I run this at a pc which has also a local rtl-sdr it always chooses rtl device 0
i just made a quick test with a locally attached dongle and GRC and can't confirm this.
The commando used on both systems is python multimode.py --devinfo=rtl_tcp= 192.168.0.50:1234
Is it also the case when you use rtl_tcp=192.168.0.50:1234 in GRC?
Best regards, Dimitri