Lowrance net problem

Guys
I have a problem getting my network to work on my boat. I have 2- lcx-27, 1-lms520, and a 3000 puck on my boat. I have one double T and two single T’s with 120 ends on each end of the system. from the four T fitting a cord goes to each units and one to the puck. Two units on the dash and one unit on the bow with the puck mounted on the bow in clear view. Each location has a new blue end power cord with the nema 2000 wires/head power wires hooked up to 12vdc.
Ploblem is I can’t get all three unit’s to hook up to GPS singal. Only one or two units at a time will hook up and show GPS info. If I move the units around in different locations, only the 520 and one of the 27’s will get GPS signal. The other lcx 27 aways says GPS not responding no matter of it’s location. The other two units will show GPS info but, when you go to the memu of NEMA 2000 on either unit it dosn’t show it see’s the other units just the 3000 puck. If I just set up a simple system of one unit and the 3000 puck, The 520 and one of the lcx 27 works just fine and the other lcx 27 dosn’t hook up with the gps.
What am I doing wrong or do I have a bad unit? THanks for any help.
matt