This appears to be closely related to
WFCORE-3884, though the stacktrace is slightly different.
"We are using JBoss EAP 7.3.7.GA version. While calling a remote EJB from the ejb client application we are getting below error in the server log. Then the the client application gets timed out.
Caused by: java.lang.ClassNotFoundException: com.sun.jndi.ldap.LdapCtxFactory from [Module "org.wildfly.extension.io" version 10.1.20.Final-redhat-00001 from local module loader @5f2108b5 (finder: local module finder @31a5c39e (roots: /ext/app/Delta_736/software/jboss/Fileloading/modules,/ext/app/Delta_736/software/jboss/Fileloading/modules/system/layers/base))]"
The same issue does not happen on EAP 7.2.8.
This looks like a TCCL bug, it should not be trying to load login classes from the org.wildfly.extension.io's module's classloader.