We see that the nodes can get disconnected, but they continue mining on itself.
We ccreated the chain with the following steps :
1 - Dowloaded
https://www.multichain.com/download/bitcoin-protocol-params.dat
2 - Changed mining-requires-peers to "true"
3 - Changed ports
4 - Changed Network name to myNet
5 - Launch : multichaind myNet -daemon
6 - Sent resulting params.dat to peer node
7 - Run multichaind myNet -daemon on peer node
The issue was before bullet 6, when the first node started, it commenced to mine right away.