Rtk here plus with 20 drones (rtk fix problem)

I am using RTK Here plus on omnibus f4 …my target is to get rtk fix on 20 drones…i achieve 4cm during field survey on base station…
my problems are:

  1. I am using ebyte E62 with Airdata rate (bps) 64Kbps , when the transmission is for a single node after 4 minute it continuously remains in rtk fix…but when i broadcast it mostly remains in rtk float , and sometimes rtk fix…another thing is when it changes from rtk float to fix and vice versa the drone height changes to 1-2 meter…
    2.is there any other module that can be used to transfer rtk correction …
    3.Anything specific to change for better performance
    4.DRONE SHOULD BE UNDER 300 grams