4250 AV bandwidth issue

I have the program pc using vmix to the main switch then running the cat6 channel out100" to the 2nd switch which pushes out NDI to two tv's via cat6 to NDI 4K magewells conversion to hdmi.  I can push content via vmix to one screen with no audio issues from video sources.  If I push to both tv's I get audio garble.... Video looks fine.  Why is this happening?  Is it exceeding the one Gig limit from the 2nd switch? I thought the switch can distribute up to 1G stream/source with a maximum of 24G for total distribution.  Why is the 2nd switch seemingly effecting the audio when pushing to two screens?  The source stream from the main switch is and pc works fine and is sending most likely well under 1G.  I am looking at running another Cat6 with L adapters from between the switches to get 2G or a fiber pair but I don't understand why my audio is faulty when the 2nd switch pushes that out.  

Any help appreciated... Thanks...