Explora 2 upgrade issues

[Smurf007]

Good day. Hoping someone can point me in the right direction. So I went from 1 explora and 2 X 4u hd decoders to 2 X explorers and 1 X 4u hd. Everything was working fine until the new explorer replaced one of the 4u decoders. After installing, the unit updated software and I changed the user frequencies so the primary and secondary don't clash. The problem now is that 4u decoder works for about 10min then displays waiting for communication from primary decoder. The RF on all secondary tvs cannot be picked up off the heart beat cable. Is this a software issue? I had to run a new heart beat between primary explorer and 4u hd just to get the 4u decoder to work. But I need to get the RF on the secondary tvs to pick up all three decoders heart beat. Setup. 80cm dish with smart lnb. All decoders less than 10m from one another. Heart beat from primary explorer( older model) to newer secondary explorer via Ellie's tv link (tvl3xv) 3outputs used to secondary tvs. Then the same heart beat from primary explorer is cut in via another tvl3xv to the 4u hd and outputs used for secondary tvs.