In a scenario with servers an echo server and an http server were utilized on node0.   Testing of node4-to-node0s connectivity are conducted; sometimes tried echo, sometimes http. Sometimes ping was tested. When it came to stunnel in particular http was put to the test and it was successful. 

However echo nor ping weren't tested.  By adding those additional tests would they have gone through or not?

Would an end-user be aware of any arrangement that could broaden coverage to all traffic seeking to pass from node4 to node0 so that, independent of service or protocol, anything addressed between the two nodes would be successfully encrypted and tunneled through?

tunnel endpoints here 10.1.1.2 node4 enp03 10.1.1.0/24 10.1.1.1 enp0s8 or here 8 node3 100.1.1.1 enp0s3 100.1.1.0/24 100.1.1.254 enpos8 node2 client-to-server blocking firewall here 200.2.2.254 enp0s3 200.2.2.0/24 clients here 200.2.2.1 en p0s8 8 node1 10.2.2.1 enp0s:3 10.2.2.0/24 10.2.2.2 enp0s3 node0 servers here