Rover doesnt change to float only stay in 3D/DGNSS

hi friends
i configured my rover and base properly as descripted in the manual. Base get into TIME mode but Rover get into 3D/DGNSS/FLOAT mode only for one second and change back to 3D/DGNSS.

Base:
Survey-in successfully finished
RTCM3 1005 1077 1087 1127 1230 messages enable
CFG devices all selected
Baudrate 115200
but in Messages RTCM3 messages can not be seen

Rover:
disable all NMEA message
enable NAV-POS-LLH / NAV-STATUS / NAV-SOL / NAV-VELNED
NAV5 using 8-airborne<4g
CFG devices all selected
PRT-Baudrate 115200
RATE-Period 200ms

what could gone wrong? Any idea?
thanks in advance!

What radio link do you use? Are the baudrates configured?

I’m using TCP to transfer the corrections by str2str application between rover and base
20180403_1