Having a self-signed entity certificate can not establish a chain of trust. Using such setups is a legacy thing not really accomplishing the trust that you want. If you insist you can still get it to work by having your own verify_fun in an Erlang client that accepts the selfsigned error, and even if you check that it is an expected self-signed cert you do not achieve the trust that you get with a chain. For other clients there exists similar tricks, but I do not recommend those solutions if you really care about authenticity.