Network rendering not using all gpus

[Sabour7]

I have 3 machines on my network currently. Two Mac pros each with 3 nvidia Gp100’s and a Windows 10 machine with 4 gp100’s. Main machine is Mac Pro with 3 gp100’s in cubix expander chassis. Network sees two slaves and works with 7gpus on top of the 3 on the Mac Pro but after a small amount of render time, the 4 Gpus on the windows side are no longer used. Render windows shows 3/7 gpus with 2/2 slaves.

Any ideas?