VAVA monitor help!

Li

I bought a VAVA monitor system since I’ll be having 3 under 3. I tried to set up today and my one monitor says it’s out of range. My rinky dinky vtech monitor has no connectivity issues- and the range on the VAVA is supposed to be better. Has anyone had this issue? Are there any hacks to improve range?? We opted for this option since it’s non wifi and can have 3 monitors. I need to make this work- please help!!