I have setu config servers and started as well but not able to connect.
vagrant@m103:/var/mongodb/pki$ mongo --port 26001
MongoDB shell version v3.6.15
connecting to: mongodb://127.0.0.1:26001/?gssapiServiceName=mongodb
2019-12-20T00:21:54.068+0000 W NETWORK [thread1] Failed to connect to 127.0.0.1:26001, in(checking socket for error after poll), reason: Connection refused
2019-12-20T00:21:54.068+0000 E QUERY [thread1] Error: couldn’t connect to server 127.0.0.1:26001, connection attempt failed :
exception: connect failed