There are several possible causes. See if you can check with them.
(1) Make sure you are using the same set of crypto-config for *all* nodes, and do not use cryptogen on each of node (then they will have different set of crypto)
(2) Check if hosts are well defined. You can check on each peer node
docker exec peer0.orgn.example.com cat /etc/hosts
And see each host can see other nodes (peer and orderer).
(3) Make sure the ports are opened for communication.
See if this helps. If not, let me know what version you are using and I will cross-check whether it is another version problem.