split system after network change

I had a split system. 
on S1 app was two ZP 100.

on S2 app was playbar, an two one’s

i updated WiFi network and created S1 as above then set up S2 as above. 
when I went back to use S1 system all components have disappeared and S1 now says all components can use S2. 
where have my S1 components gone?

can I get S1 working again or will I have to downgrade S2 components to S1 set up as S1 then split system again?

if the latter what a pain and mess up!